Dirk M. Elston, MD

An ancient tree of the Ginkgoaceae family, Ginkgo biloba is known as a living fossil because its genome has been identified in fossils older than 200 million years.¹ An individual tree can live longer than 1000 years. Originating in China, G biloba (here, “ginkgo”) is cultivated worldwide for its attractive foliage (Figure 1). Ginkgo extract has long been used in traditional Chinese medicine; however, contact with the plant proper can provoke allergic contact dermatitis.

Dermatitis-Inducing Components

The allergenic component of the ginkgo tree is ginkgolic acid, which is structurally similar to urushiol and anacardic acid.^2,3 This compound can cause a cross-reaction in a person previously sensitized by contact with other plants. Urushiol is found in poison ivy(Toxicodendron radicans); anacardic acid is found in the cashew tree (Anacardium occidentale). Both plants belong to the family Anacardiaceae, commonly known as the cashew family.

Members of Anacardiaceae are the most common causes of plant-induced allergic contact dermatitis and include the cashew tree, mango tree, poison ivy, poison oak, and poison sumac. These plants can cross-react to cause contact dermatitis (Table).³ Patch tests have revealed that some individuals who are sensitive to components of the ginkgo tree also demonstrate sensitivity to poison ivy and poison sumac^4,5; countering this finding, Lepoittevin and colleagues⁶ demonstrated in animal studies that there was no cross-reactivity between ginkgo and urushiol, suggesting that patients with a reported cross-reaction might truly have been previously sensitized to both plants. In general, patients who have a history of a reaction to any Anacardiaceae plant should take precautions when handling them.

Therapeutic Benefit of Ginkgo

Ginkgo extract is sold as the herbal supplement EGB761, which acts as an antioxidant.⁷ In France, Germany, and China, it is a commonly prescribed herbal medicine.⁸ It is purported to support memory and attention; studies have shown improvement in cognition and in involvement with activities of daily living for patients with dementia.^9,10 Ginkgo extract might lessen peripheral vascular disease and cerebral circulatory disease, having been shown in vitro and in animal models to prevent platelet aggregation induced by platelet-activating factor and to stimulate vasodilation by increasing production of nitric oxide.^11,12

Furthermore, purified ginkgo extract might have beneficial effects on skin. A study in rats showed that when intraperitoneal ginkgo extract was given prior to radiation therapy, 100% of rats receiving placebo developed radiation dermatitis vs 13% of those that received ginkgo extract (P<.0001). An excisional skin biopsy showed a decrease in markers of oxidative stress in rats that received ginkgo extract prior to radiation.⁷

A randomized, double-blind clinical trial showed a significant reduction in disease progression in vitiligo patients assigned to receive ginkgo extract orally compared to placebo (P=.006).¹³ Research for many possible uses of ginkgo extract is ongoing.

Cutaneous Manifestations

Contact with the fruit of the ginkgo tree can induce allergic contact dermatitis,¹⁴ most often as erythematous papules, vesicles, and in some cases edema.^5,15

Exposures While Picking Berries—In 1939, Bolus¹⁵ reported the case of a patient who presented with edema, erythema, and vesicular lesions involving the hands and face after picking berries from a ginkgo tree. Later, patch testing on this patient, using ginkgo fruit, resulted in burning and stinging that necessitated removal of the patch, suggesting an irritant reaction. This was followed by a vesicular reaction that then developed within 24 hours, which was more consistent with allergy. Similarly, in 1988, a case series of contact dermatitis was reported in 3 patients after gathering ginkgo fruit.⁵

Incidental Exposure While Walking—In 1965, dermatitis broke out in 35 high school students, mainly affecting exposed portions of the leg, after ginkgo fruit fell and its pulp was exposed on a path at their school.⁴ Subsequently, patch testing was performed on 29 volunteers—some who had been exposed to ginkgo on that path, others without prior exposure. It was established that testing with ginkgo pulp directly caused an irritant reaction in all students, regardless of prior ginkgo exposure, but all prior ginkgo-exposed students in this study reacted positively to an acetone extract of ginkgo pulp and either poison ivy extract or pentadecylcatechol.⁴

Systemic Contact After Eating Fruit—An illustrative case of dermatitis, stomatitis, and proctitis was reported in a man with history of poison oak contact dermatitis who had eaten fruit from a ginkgo tree, suggesting systemic contact dermatitis. Weeks after resolution of symptoms, he reacted positively to ginkgo fruit and poison ivy extracts on patch testing.¹⁶

Ginkgo dermatitis tends to resolve upon removal of the inciting agent and application of a topical steroid.^8,17 Although many reported cases involve the fruit, allergic contact dermatitis can result from exposure to any part of the plant. In a reported case, a woman developed airborne contact dermatitis from working with sarcotesta of the ginkgo plant.¹⁸ Despite wearing rubber gloves, she broke out 1 week after exposure with erythema on the face and arms and severe facial edema.

Ginkgo leaves also can cause allergic contact dermatitis.¹⁹ Precautions should be taken when handling any component of the ginkgo tree.

Oral ginkgo supplementation has been implicated in a variety of other cutaneous reactions—from benign to life-threatening. When the ginkgo allergen concentration is too high within the supplement, as has been noted in some formulations, patients have presented with a diffuse morbilliform eruption within 1 or 2 weeks after taking ginkgo.²⁰ One patient—who was not taking any other medication—experienced an episode of acute generalized exanthematous pustulosis 48 hours after taking ginkgo.²¹ Ingestion of ginkgo extract also has been associated with Stevens-Johnson syndrome.^22-24

Other Adverse Reactions

The adverse effects of ginkgo supplement vary widely. In addition to dermatitis, ginkgo supplement can cause headaches, palpitations, tachycardia, vasculitis, nausea, and other symptoms.¹⁴

Metabolic Disturbance—One patient taking ginkgo who died after a seizure was found to have subtherapeutic levels of valproate and phenytoin,²⁵ which could be due to ginkgo’s effect on cytochrome p450 enzyme CYP2C19.²⁶ Ginkgo interactions with many cytochrome enzymes have been studied for potential drug interactions. Any other direct effects remain variable and controversial.^27,28

Hemorrhage—Another serious effect associated with taking ginkgo supplements is hemorrhage, often in conjunction with warfarin¹⁴; however, a meta-analysis indicated that ginkgo generally does not increase the risk of bleeding.²⁹ Other studies have shown that taking ginkgo with warfarin showed no difference in clotting status, and ginkgo with aspirin resulted in no clinically significant difference in bruising, bleeding, or platelet function in an analysis over a period of 1 month.^30,31 These findings notwithstanding, pregnant women, surgical patients, and those taking a blood thinner are advised as a general precaution not to take ginkgo extract.

Carcinogenesis—Ginkgo extract has antioxidant properties, but there is evidence that it might act as a carcinogen. An animal study reported by the US National Toxicology Program found that ginkgo induced mutagenic activity in the liver, thyroid, and nose of mice and rats. Over time, rodent liver underwent changes consistent with hepatic enzyme induction.³² More research is needed to clarify the role of ginkgo in this process.

Toxicity by Ingestion—Ginkgo seeds can cause food poisoning due to the compound 4’-O-methylpyridoxine (also known as ginkgotoxin).³³ Because methylpyridoxine can cause depletion of pyridoxal phosphate (a form of vitamin B₆ necessary for the synthesis of γ-aminobutyric acid), overconsumption of ginkgo seeds, even when fully cooked, might result in convulsions and even death.³³

Nomenclature and Distribution of Plants

Gingko biloba belongs to the Ginkgoaceae family (class Ginkgophytes). The tree originated in China but might no longer exist in a truly wild form. It is grown worldwide for its beauty and longevity. The female ginkgo tree is a gymnosperm, producing fruit with seeds that are not coated by an ovary wall¹⁵; male (nonfruiting) trees are preferentially planted because the fruit is surrounded by a pulp that, when dropped, emits a sour smell described variously as rancid butter, vomit, or excrement.⁵

Identifying Features and Plant Facts

The deciduous ginkgo tree has unique fan-shaped leaves and is cultivated for its beauty and resistance to disease (Figure 2).^4,34 It is nicknamed the maidenhair tree because the leaves are similar to the pinnae of the maidenhair fern.³⁴ Because G biloba is resistant to pollution, it often is planted along city streets.¹⁷ The leaf—5- to 8-cm wide and a symbol of the city of Tokyo, Japan³⁴—grows in clusters (Figure 3)⁵ and is green but turns yellow before it falls in autumn.³⁴ Leaf veins branch out into the blade without anastomosing.³⁴

Male flowers grow in a catkinlike pattern; female flowers grow on long stems.⁵ The fruit is small, dark, and shriveled, with a hint of silver⁴; it typically is 2 to 2.5 cm in diameter and contains the ginkgo nut or seed. The kernel of the ginkgo nut is edible when roasted and is used in traditional Chinese and Japanese cuisine as a dish served on special occasions in autumn.³³

Final Thoughts

Given that G biloba is a beautiful, commonly planted ornamental tree, gardeners and landscapers should be aware of the risk for allergic contact dermatitis and use proper protection. Dermatologists should be aware of its cross-reactivity with other common plants such as poison ivy and poison oak to help patients identify the cause of their reactions and avoid the inciting agent. Because ginkgo extract also can cause a cutaneous reaction or interact with other medications, providers should remember to take a thorough medication history that includes herbal medicines and supplements.

An ancient tree of the Ginkgoaceae family, Ginkgo biloba is known as a living fossil because its genome has been identified in fossils older than 200 million years.¹ An individual tree can live longer than 1000 years. Originating in China, G biloba (here, “ginkgo”) is cultivated worldwide for its attractive foliage (Figure 1). Ginkgo extract has long been used in traditional Chinese medicine; however, contact with the plant proper can provoke allergic contact dermatitis.

Dermatitis-Inducing Components

The allergenic component of the ginkgo tree is ginkgolic acid, which is structurally similar to urushiol and anacardic acid.^2,3 This compound can cause a cross-reaction in a person previously sensitized by contact with other plants. Urushiol is found in poison ivy(Toxicodendron radicans); anacardic acid is found in the cashew tree (Anacardium occidentale). Both plants belong to the family Anacardiaceae, commonly known as the cashew family.

Members of Anacardiaceae are the most common causes of plant-induced allergic contact dermatitis and include the cashew tree, mango tree, poison ivy, poison oak, and poison sumac. These plants can cross-react to cause contact dermatitis (Table).³ Patch tests have revealed that some individuals who are sensitive to components of the ginkgo tree also demonstrate sensitivity to poison ivy and poison sumac^4,5; countering this finding, Lepoittevin and colleagues⁶ demonstrated in animal studies that there was no cross-reactivity between ginkgo and urushiol, suggesting that patients with a reported cross-reaction might truly have been previously sensitized to both plants. In general, patients who have a history of a reaction to any Anacardiaceae plant should take precautions when handling them.

Therapeutic Benefit of Ginkgo

Ginkgo extract is sold as the herbal supplement EGB761, which acts as an antioxidant.⁷ In France, Germany, and China, it is a commonly prescribed herbal medicine.⁸ It is purported to support memory and attention; studies have shown improvement in cognition and in involvement with activities of daily living for patients with dementia.^9,10 Ginkgo extract might lessen peripheral vascular disease and cerebral circulatory disease, having been shown in vitro and in animal models to prevent platelet aggregation induced by platelet-activating factor and to stimulate vasodilation by increasing production of nitric oxide.^11,12

Furthermore, purified ginkgo extract might have beneficial effects on skin. A study in rats showed that when intraperitoneal ginkgo extract was given prior to radiation therapy, 100% of rats receiving placebo developed radiation dermatitis vs 13% of those that received ginkgo extract (P<.0001). An excisional skin biopsy showed a decrease in markers of oxidative stress in rats that received ginkgo extract prior to radiation.⁷

A randomized, double-blind clinical trial showed a significant reduction in disease progression in vitiligo patients assigned to receive ginkgo extract orally compared to placebo (P=.006).¹³ Research for many possible uses of ginkgo extract is ongoing.

Cutaneous Manifestations

Contact with the fruit of the ginkgo tree can induce allergic contact dermatitis,¹⁴ most often as erythematous papules, vesicles, and in some cases edema.^5,15

Exposures While Picking Berries—In 1939, Bolus¹⁵ reported the case of a patient who presented with edema, erythema, and vesicular lesions involving the hands and face after picking berries from a ginkgo tree. Later, patch testing on this patient, using ginkgo fruit, resulted in burning and stinging that necessitated removal of the patch, suggesting an irritant reaction. This was followed by a vesicular reaction that then developed within 24 hours, which was more consistent with allergy. Similarly, in 1988, a case series of contact dermatitis was reported in 3 patients after gathering ginkgo fruit.⁵

Incidental Exposure While Walking—In 1965, dermatitis broke out in 35 high school students, mainly affecting exposed portions of the leg, after ginkgo fruit fell and its pulp was exposed on a path at their school.⁴ Subsequently, patch testing was performed on 29 volunteers—some who had been exposed to ginkgo on that path, others without prior exposure. It was established that testing with ginkgo pulp directly caused an irritant reaction in all students, regardless of prior ginkgo exposure, but all prior ginkgo-exposed students in this study reacted positively to an acetone extract of ginkgo pulp and either poison ivy extract or pentadecylcatechol.⁴

Systemic Contact After Eating Fruit—An illustrative case of dermatitis, stomatitis, and proctitis was reported in a man with history of poison oak contact dermatitis who had eaten fruit from a ginkgo tree, suggesting systemic contact dermatitis. Weeks after resolution of symptoms, he reacted positively to ginkgo fruit and poison ivy extracts on patch testing.¹⁶

Ginkgo dermatitis tends to resolve upon removal of the inciting agent and application of a topical steroid.^8,17 Although many reported cases involve the fruit, allergic contact dermatitis can result from exposure to any part of the plant. In a reported case, a woman developed airborne contact dermatitis from working with sarcotesta of the ginkgo plant.¹⁸ Despite wearing rubber gloves, she broke out 1 week after exposure with erythema on the face and arms and severe facial edema.

Ginkgo leaves also can cause allergic contact dermatitis.¹⁹ Precautions should be taken when handling any component of the ginkgo tree.

Oral ginkgo supplementation has been implicated in a variety of other cutaneous reactions—from benign to life-threatening. When the ginkgo allergen concentration is too high within the supplement, as has been noted in some formulations, patients have presented with a diffuse morbilliform eruption within 1 or 2 weeks after taking ginkgo.²⁰ One patient—who was not taking any other medication—experienced an episode of acute generalized exanthematous pustulosis 48 hours after taking ginkgo.²¹ Ingestion of ginkgo extract also has been associated with Stevens-Johnson syndrome.^22-24

Other Adverse Reactions

The adverse effects of ginkgo supplement vary widely. In addition to dermatitis, ginkgo supplement can cause headaches, palpitations, tachycardia, vasculitis, nausea, and other symptoms.¹⁴

Metabolic Disturbance—One patient taking ginkgo who died after a seizure was found to have subtherapeutic levels of valproate and phenytoin,²⁵ which could be due to ginkgo’s effect on cytochrome p450 enzyme CYP2C19.²⁶ Ginkgo interactions with many cytochrome enzymes have been studied for potential drug interactions. Any other direct effects remain variable and controversial.^27,28

Hemorrhage—Another serious effect associated with taking ginkgo supplements is hemorrhage, often in conjunction with warfarin¹⁴; however, a meta-analysis indicated that ginkgo generally does not increase the risk of bleeding.²⁹ Other studies have shown that taking ginkgo with warfarin showed no difference in clotting status, and ginkgo with aspirin resulted in no clinically significant difference in bruising, bleeding, or platelet function in an analysis over a period of 1 month.^30,31 These findings notwithstanding, pregnant women, surgical patients, and those taking a blood thinner are advised as a general precaution not to take ginkgo extract.

Carcinogenesis—Ginkgo extract has antioxidant properties, but there is evidence that it might act as a carcinogen. An animal study reported by the US National Toxicology Program found that ginkgo induced mutagenic activity in the liver, thyroid, and nose of mice and rats. Over time, rodent liver underwent changes consistent with hepatic enzyme induction.³² More research is needed to clarify the role of ginkgo in this process.

Toxicity by Ingestion—Ginkgo seeds can cause food poisoning due to the compound 4’-O-methylpyridoxine (also known as ginkgotoxin).³³ Because methylpyridoxine can cause depletion of pyridoxal phosphate (a form of vitamin B₆ necessary for the synthesis of γ-aminobutyric acid), overconsumption of ginkgo seeds, even when fully cooked, might result in convulsions and even death.³³

Nomenclature and Distribution of Plants

Gingko biloba belongs to the Ginkgoaceae family (class Ginkgophytes). The tree originated in China but might no longer exist in a truly wild form. It is grown worldwide for its beauty and longevity. The female ginkgo tree is a gymnosperm, producing fruit with seeds that are not coated by an ovary wall¹⁵; male (nonfruiting) trees are preferentially planted because the fruit is surrounded by a pulp that, when dropped, emits a sour smell described variously as rancid butter, vomit, or excrement.⁵

Identifying Features and Plant Facts

The deciduous ginkgo tree has unique fan-shaped leaves and is cultivated for its beauty and resistance to disease (Figure 2).^4,34 It is nicknamed the maidenhair tree because the leaves are similar to the pinnae of the maidenhair fern.³⁴ Because G biloba is resistant to pollution, it often is planted along city streets.¹⁷ The leaf—5- to 8-cm wide and a symbol of the city of Tokyo, Japan³⁴—grows in clusters (Figure 3)⁵ and is green but turns yellow before it falls in autumn.³⁴ Leaf veins branch out into the blade without anastomosing.³⁴

Male flowers grow in a catkinlike pattern; female flowers grow on long stems.⁵ The fruit is small, dark, and shriveled, with a hint of silver⁴; it typically is 2 to 2.5 cm in diameter and contains the ginkgo nut or seed. The kernel of the ginkgo nut is edible when roasted and is used in traditional Chinese and Japanese cuisine as a dish served on special occasions in autumn.³³

Final Thoughts

Given that G biloba is a beautiful, commonly planted ornamental tree, gardeners and landscapers should be aware of the risk for allergic contact dermatitis and use proper protection. Dermatologists should be aware of its cross-reactivity with other common plants such as poison ivy and poison oak to help patients identify the cause of their reactions and avoid the inciting agent. Because ginkgo extract also can cause a cutaneous reaction or interact with other medications, providers should remember to take a thorough medication history that includes herbal medicines and supplements.

An ancient tree of the Ginkgoaceae family, Ginkgo biloba is known as a living fossil because its genome has been identified in fossils older than 200 million years.¹ An individual tree can live longer than 1000 years. Originating in China, G biloba (here, “ginkgo”) is cultivated worldwide for its attractive foliage (Figure 1). Ginkgo extract has long been used in traditional Chinese medicine; however, contact with the plant proper can provoke allergic contact dermatitis.

Dermatitis-Inducing Components

The allergenic component of the ginkgo tree is ginkgolic acid, which is structurally similar to urushiol and anacardic acid.^2,3 This compound can cause a cross-reaction in a person previously sensitized by contact with other plants. Urushiol is found in poison ivy(Toxicodendron radicans); anacardic acid is found in the cashew tree (Anacardium occidentale). Both plants belong to the family Anacardiaceae, commonly known as the cashew family.

Members of Anacardiaceae are the most common causes of plant-induced allergic contact dermatitis and include the cashew tree, mango tree, poison ivy, poison oak, and poison sumac. These plants can cross-react to cause contact dermatitis (Table).³ Patch tests have revealed that some individuals who are sensitive to components of the ginkgo tree also demonstrate sensitivity to poison ivy and poison sumac^4,5; countering this finding, Lepoittevin and colleagues⁶ demonstrated in animal studies that there was no cross-reactivity between ginkgo and urushiol, suggesting that patients with a reported cross-reaction might truly have been previously sensitized to both plants. In general, patients who have a history of a reaction to any Anacardiaceae plant should take precautions when handling them.

Therapeutic Benefit of Ginkgo

Ginkgo extract is sold as the herbal supplement EGB761, which acts as an antioxidant.⁷ In France, Germany, and China, it is a commonly prescribed herbal medicine.⁸ It is purported to support memory and attention; studies have shown improvement in cognition and in involvement with activities of daily living for patients with dementia.^9,10 Ginkgo extract might lessen peripheral vascular disease and cerebral circulatory disease, having been shown in vitro and in animal models to prevent platelet aggregation induced by platelet-activating factor and to stimulate vasodilation by increasing production of nitric oxide.^11,12

Furthermore, purified ginkgo extract might have beneficial effects on skin. A study in rats showed that when intraperitoneal ginkgo extract was given prior to radiation therapy, 100% of rats receiving placebo developed radiation dermatitis vs 13% of those that received ginkgo extract (P<.0001). An excisional skin biopsy showed a decrease in markers of oxidative stress in rats that received ginkgo extract prior to radiation.⁷

A randomized, double-blind clinical trial showed a significant reduction in disease progression in vitiligo patients assigned to receive ginkgo extract orally compared to placebo (P=.006).¹³ Research for many possible uses of ginkgo extract is ongoing.

Cutaneous Manifestations

Contact with the fruit of the ginkgo tree can induce allergic contact dermatitis,¹⁴ most often as erythematous papules, vesicles, and in some cases edema.^5,15

Exposures While Picking Berries—In 1939, Bolus¹⁵ reported the case of a patient who presented with edema, erythema, and vesicular lesions involving the hands and face after picking berries from a ginkgo tree. Later, patch testing on this patient, using ginkgo fruit, resulted in burning and stinging that necessitated removal of the patch, suggesting an irritant reaction. This was followed by a vesicular reaction that then developed within 24 hours, which was more consistent with allergy. Similarly, in 1988, a case series of contact dermatitis was reported in 3 patients after gathering ginkgo fruit.⁵

Incidental Exposure While Walking—In 1965, dermatitis broke out in 35 high school students, mainly affecting exposed portions of the leg, after ginkgo fruit fell and its pulp was exposed on a path at their school.⁴ Subsequently, patch testing was performed on 29 volunteers—some who had been exposed to ginkgo on that path, others without prior exposure. It was established that testing with ginkgo pulp directly caused an irritant reaction in all students, regardless of prior ginkgo exposure, but all prior ginkgo-exposed students in this study reacted positively to an acetone extract of ginkgo pulp and either poison ivy extract or pentadecylcatechol.⁴

Systemic Contact After Eating Fruit—An illustrative case of dermatitis, stomatitis, and proctitis was reported in a man with history of poison oak contact dermatitis who had eaten fruit from a ginkgo tree, suggesting systemic contact dermatitis. Weeks after resolution of symptoms, he reacted positively to ginkgo fruit and poison ivy extracts on patch testing.¹⁶

Ginkgo dermatitis tends to resolve upon removal of the inciting agent and application of a topical steroid.^8,17 Although many reported cases involve the fruit, allergic contact dermatitis can result from exposure to any part of the plant. In a reported case, a woman developed airborne contact dermatitis from working with sarcotesta of the ginkgo plant.¹⁸ Despite wearing rubber gloves, she broke out 1 week after exposure with erythema on the face and arms and severe facial edema.

Ginkgo leaves also can cause allergic contact dermatitis.¹⁹ Precautions should be taken when handling any component of the ginkgo tree.

Oral ginkgo supplementation has been implicated in a variety of other cutaneous reactions—from benign to life-threatening. When the ginkgo allergen concentration is too high within the supplement, as has been noted in some formulations, patients have presented with a diffuse morbilliform eruption within 1 or 2 weeks after taking ginkgo.²⁰ One patient—who was not taking any other medication—experienced an episode of acute generalized exanthematous pustulosis 48 hours after taking ginkgo.²¹ Ingestion of ginkgo extract also has been associated with Stevens-Johnson syndrome.^22-24

Other Adverse Reactions

The adverse effects of ginkgo supplement vary widely. In addition to dermatitis, ginkgo supplement can cause headaches, palpitations, tachycardia, vasculitis, nausea, and other symptoms.¹⁴

Metabolic Disturbance—One patient taking ginkgo who died after a seizure was found to have subtherapeutic levels of valproate and phenytoin,²⁵ which could be due to ginkgo’s effect on cytochrome p450 enzyme CYP2C19.²⁶ Ginkgo interactions with many cytochrome enzymes have been studied for potential drug interactions. Any other direct effects remain variable and controversial.^27,28

Hemorrhage—Another serious effect associated with taking ginkgo supplements is hemorrhage, often in conjunction with warfarin¹⁴; however, a meta-analysis indicated that ginkgo generally does not increase the risk of bleeding.²⁹ Other studies have shown that taking ginkgo with warfarin showed no difference in clotting status, and ginkgo with aspirin resulted in no clinically significant difference in bruising, bleeding, or platelet function in an analysis over a period of 1 month.^30,31 These findings notwithstanding, pregnant women, surgical patients, and those taking a blood thinner are advised as a general precaution not to take ginkgo extract.

Carcinogenesis—Ginkgo extract has antioxidant properties, but there is evidence that it might act as a carcinogen. An animal study reported by the US National Toxicology Program found that ginkgo induced mutagenic activity in the liver, thyroid, and nose of mice and rats. Over time, rodent liver underwent changes consistent with hepatic enzyme induction.³² More research is needed to clarify the role of ginkgo in this process.

Toxicity by Ingestion—Ginkgo seeds can cause food poisoning due to the compound 4’-O-methylpyridoxine (also known as ginkgotoxin).³³ Because methylpyridoxine can cause depletion of pyridoxal phosphate (a form of vitamin B₆ necessary for the synthesis of γ-aminobutyric acid), overconsumption of ginkgo seeds, even when fully cooked, might result in convulsions and even death.³³

Nomenclature and Distribution of Plants

Gingko biloba belongs to the Ginkgoaceae family (class Ginkgophytes). The tree originated in China but might no longer exist in a truly wild form. It is grown worldwide for its beauty and longevity. The female ginkgo tree is a gymnosperm, producing fruit with seeds that are not coated by an ovary wall¹⁵; male (nonfruiting) trees are preferentially planted because the fruit is surrounded by a pulp that, when dropped, emits a sour smell described variously as rancid butter, vomit, or excrement.⁵

Identifying Features and Plant Facts

The deciduous ginkgo tree has unique fan-shaped leaves and is cultivated for its beauty and resistance to disease (Figure 2).^4,34 It is nicknamed the maidenhair tree because the leaves are similar to the pinnae of the maidenhair fern.³⁴ Because G biloba is resistant to pollution, it often is planted along city streets.¹⁷ The leaf—5- to 8-cm wide and a symbol of the city of Tokyo, Japan³⁴—grows in clusters (Figure 3)⁵ and is green but turns yellow before it falls in autumn.³⁴ Leaf veins branch out into the blade without anastomosing.³⁴

Male flowers grow in a catkinlike pattern; female flowers grow on long stems.⁵ The fruit is small, dark, and shriveled, with a hint of silver⁴; it typically is 2 to 2.5 cm in diameter and contains the ginkgo nut or seed. The kernel of the ginkgo nut is edible when roasted and is used in traditional Chinese and Japanese cuisine as a dish served on special occasions in autumn.³³

Final Thoughts

Given that G biloba is a beautiful, commonly planted ornamental tree, gardeners and landscapers should be aware of the risk for allergic contact dermatitis and use proper protection. Dermatologists should be aware of its cross-reactivity with other common plants such as poison ivy and poison oak to help patients identify the cause of their reactions and avoid the inciting agent. Because ginkgo extract also can cause a cutaneous reaction or interact with other medications, providers should remember to take a thorough medication history that includes herbal medicines and supplements.

Incidence and Characteristics

Mosquitoes are insects categorized into the order of Diptera and family of Culicidae, and more than 3500 different species have been identified.¹ In the United States, the most common genus of mosquitoes is Aedes, with other common genera including Culex, Anopheles, Culiseta, and Coquillettidia. Most bites are performed by female rather than male mosquitoes, as it serves to complete their life cycle (Figure 1).¹

There are a variety of possible reactions to mosquito bites. Severe local reactions that are large (papules >30 mm in diameter) or are accompanied by systemic manifestations are referred to as hypersensitivity to mosquito bites (HMB).² These hypersensitivity reactions vary according to multiple factors, including comorbid conditions, genetic predisposition, and geographic location. The majority of the world’s population will exhibit local reactions to mosquito bites at some point during life, with the median age of onset of the first bite at 2 years of age.³ In a study by Arias-Cruz et al,⁴ the incidence of patient-reported large local reactions was 2.5%. Hypersensitivity to mosquito bites, perhaps the most rare reaction, is more common among Asian and Central American children.⁵ The median age of diagnosis for HMB is 7 years, and most reactions occur during the first 2 decades of life.^6,7

Clinical Presentation

Mosquitoes bite vertebrates in an attempt to feed and thus must locate the host’s blood vessels through a process known as probing, which often necessitates changing the bite site several times. Once the vessel is located and lacerated, the mosquito feeds either from the vessel directly or the hematoma around it. Not only does the bite cause trauma to the skin, but a cutaneous reaction also may occur in response to salivary gland secretions that concurrently are deposited in the host tissue.⁸ Mosquitoes’ salivary gland components are the primary cause of cutaneous reactions, as one study showed that bites from mosquitoes lacking salivary gland ducts were not associated with these reactions.⁹ Mosquito saliva contains a large number of compounds with biologic activities, including lysozymes, antibacterial glucosidases, anticoagulants, antiplatelet aggregating factors, and vasodilators, as well as a potentially large number of unknown allergenic proteins. As of 2016, 70 mosquito-derived allergens have been identified, but this number continues to grow.² After a bite from a mosquito, these compounds may result in host sensitization over time, though interestingly, sensitization to mosquito bites from a species different from the original offender does not occur due to lack of cross-reactivity between species.¹ 

Because mosquitoes reproduce by laying their eggs directly on or near water, people who live near bodies of water or wetlands are at the highest risk for mosquito bites. Patient factors that have been found to lead to increased rates of mosquito bites include lower microbial diversity on the skin, the presence of sweat or body odor, pregnancy, increased body temperature, type O blood, dark clothing, and perfumes.² Exaggerated bite reactions are associated with Epstein-Barr virus (EBV) infection and hematologic malignancies.¹⁰ 

Immediate hypersensitivity is mediated by a specific IgE antibody and is characterized by erythema and a wheal at the bite site that peaks within minutes of the bite. In contrast, delayed hypersensitivity is lymphocyte mediated; occurs 24 hours after the bite; and causes an indurated, pruritic, and erythematous 2- to 10-mm papule that may blister.¹¹ Although the evidence of immediate hypersensitivity disappears within hours, symptoms of delayed hypersensitivity may last days to weeks. Accompanying symptoms may include local swelling, pain, and warmth. The itch that often is experienced in conjunction with erythema and papule formation is elicited in 3 main ways: direct induction utilizing classic pruritic pathways, IgE-mediated hypersensitivity reaction to salivary components, and IgE-independent host immune response to salivary antigens. Papular urticaria is a common additional finding in children with mosquito bites.¹ As an individual is repeatedly bitten, they may undergo 5 stages of sensitization: stage I (neither immediate nor delayed reaction), stage II (delayed reaction), stage III (immediate and delayed reaction), stage IV (immediate reaction), and stage V (neither immediate or delayed reaction).¹¹

Although most mosquito bites cause common local reactions, patients rarely demonstrate systemic reactions that can be much more severe. Skeeter syndrome is a milder systemic response characterized by large local reactions (papules >30 mm in diameter) developing hours after a bite with accompanying fever.¹² The reaction typically peaks over days to weeks.² Although the reaction may resemble cellulitis clinically, a history of a preceding mosquito bite can help make the distinction.¹³ 

A more severe systemic reaction is HMB, which is characterized by intense local skin findings as well as generalized systemic symptoms. Initially, indurated, clear, or hemorrhagic bullae appear at the bite site (Figure 2). Later, there is progression to swelling, necrosis, and ulceration.¹⁰ Biopsies from the skin lesions associated with HMB reveal necrosis, interstitial and perivascular eosinophilic and lymphocytic infiltrates, and small vessels with fibrinoid necrosis.⁷ Systemically, high fever, general malaise, liver dysfunction, proteinuria, hematuria, hepatosplenomegaly, and lymph node enlargement may occur. Patients typically experience these severe symptoms each time they are bitten.¹⁰

The mechanism of the HMB reaction is complex but has a close association with natural killer (NK) cell lymphoproliferative disorder and EBV infection (Figure 3). In fact, it is not uncommon for HMB patients to develop malignant lymphomas during their clinical course, even those unrelated to EBV.¹⁴ Epstein-Barr virus, one of the human herpesviruses, produces latent infection in NK cells. It is hypothesized that after a mosquito bite, EBV may be reactivated within these cells by induced expression of the viral lytic-cycle transactivator gene BamHI Z fragment leftward open reading frame 1, BZLF1.⁶ In response to mosquito salivary gland components, CD4⁺ T cells proliferate and induce expression of the EBV oncogene latent membrane protein 1, LMP1, on NK cells, which then infiltrate the bite site.¹⁵ These EBV-infected NK cells also overexpress the Fas ligand, thus contributing to organ and tissue damage.⁶ In addition to activating oncogene expression on NK cells, T cells also activate the basophils and mast cells carrying mosquito-specific IgE, both of which also add to the severe skin reaction of HMB.¹⁵ The particular triad of HMB, chronic active EBV infection, and NK cell lymphoproliferative disorder commonly is known as HMB-EBV-NK or HEN disease.¹ Patients with HMB should be monitored for malignancy. The mortality of HMB is increased in patients in whom onset occurs when they are older than 9 years and with BZLF1 messenger RNA in skin lesions.⁶ 

Other rare reactions to mosquito bites include Wells syndrome, anaphylaxis, and superficial lymphangitis. Wells syndrome (also known as eosinophilic cellulitis) is characterized by erythematous or violaceous plaques and pruritic blisters. Although its etiology has not been defined, it is thought to be evoked or exacerbated by insect bites, with CD4⁺ T cells playing a primary role.¹ Anaphylaxis (angioedema, urticaria, and wheezing) rarely may occur due to mosquito salivary gland components but typically is caused by other stinging insects. Superficial lymphangitis, often misdiagnosed as an infection of the lymphatic system, presents within minutes as nontender pink streaks originating from the bite site. A biopsy with eosinophil and mast cell infiltrates consistent with an allergic-type reaction confirms the absence of infection. Patients respond well to glucocorticoid treatment.

Mosquitoes are vectors for many blood-borne diseases, including dengue hemorrhagic fever, malaria, Chikungunya virus, La Crosse encephalitis, St. Louis encephalitis, West Nile virus, and yellow fever.¹⁶ Additionally, scratching the bites may lead to superinfection and scarring.¹

Prevention and Treatment

Patients with known mosquito sensitivity should avoid areas of stagnant water and utilize preventative measures such as wearing protective clothing and using mosquito repellent containing DEET (N,N-diethyl-meta-toluamide), IR3535 (ethyl butylacetylaminopropionate), picaridin, or 2-undecanone (methyl nonyl ketone or IBI-246) when outdoors. Essential oils such as lemon, eucalyptus, citronella, and garlic are somewhat effective.¹ Additionally, prophylactic dosing of antihistamines may prevent milder reactions.

Although often supportive, treatment and management of mosquito bites depends on the extent of the reaction. For common local reactions, symptomatic management with topical anesthetics, calamine lotion, or corticosteroid creams is appropriate. If superinfection from scratching is a concern, antibiotics may be appropriate.

Management of more severe and systemic reactions such as HMB also is supportive, and the addition of oral corticosteroids to decrease inflammation is required.⁷ Severe HMB also has been treated with immunosuppressive and anticancer drugs, though the efficacy is limited. Venom immunotherapy is a preventative option for patients with mosquito-specific IgE antibodies, and hematopoietic stem cell transplant may be required in patients with HMB.^14,16

Conclusion

Mosquito allergens can cause a variety of reactions, ranging from those limited to the skin to those characterized by severe systemic effects. Although common local reactions can be symptomatically treated with topical medication, more severe reactions such as HMB require more involved clinical management. Hypersensitivity to mosquito bites is an important condition to recognize, as it is related to multiple organ impairment as well as later development of malignancy. Patients should be closely monitored during the entire clinical course and in the years following.

Incidence and Characteristics

Mosquitoes are insects categorized into the order of Diptera and family of Culicidae, and more than 3500 different species have been identified.¹ In the United States, the most common genus of mosquitoes is Aedes, with other common genera including Culex, Anopheles, Culiseta, and Coquillettidia. Most bites are performed by female rather than male mosquitoes, as it serves to complete their life cycle (Figure 1).¹

There are a variety of possible reactions to mosquito bites. Severe local reactions that are large (papules >30 mm in diameter) or are accompanied by systemic manifestations are referred to as hypersensitivity to mosquito bites (HMB).² These hypersensitivity reactions vary according to multiple factors, including comorbid conditions, genetic predisposition, and geographic location. The majority of the world’s population will exhibit local reactions to mosquito bites at some point during life, with the median age of onset of the first bite at 2 years of age.³ In a study by Arias-Cruz et al,⁴ the incidence of patient-reported large local reactions was 2.5%. Hypersensitivity to mosquito bites, perhaps the most rare reaction, is more common among Asian and Central American children.⁵ The median age of diagnosis for HMB is 7 years, and most reactions occur during the first 2 decades of life.^6,7

Clinical Presentation

Mosquitoes bite vertebrates in an attempt to feed and thus must locate the host’s blood vessels through a process known as probing, which often necessitates changing the bite site several times. Once the vessel is located and lacerated, the mosquito feeds either from the vessel directly or the hematoma around it. Not only does the bite cause trauma to the skin, but a cutaneous reaction also may occur in response to salivary gland secretions that concurrently are deposited in the host tissue.⁸ Mosquitoes’ salivary gland components are the primary cause of cutaneous reactions, as one study showed that bites from mosquitoes lacking salivary gland ducts were not associated with these reactions.⁹ Mosquito saliva contains a large number of compounds with biologic activities, including lysozymes, antibacterial glucosidases, anticoagulants, antiplatelet aggregating factors, and vasodilators, as well as a potentially large number of unknown allergenic proteins. As of 2016, 70 mosquito-derived allergens have been identified, but this number continues to grow.² After a bite from a mosquito, these compounds may result in host sensitization over time, though interestingly, sensitization to mosquito bites from a species different from the original offender does not occur due to lack of cross-reactivity between species.¹ 

Because mosquitoes reproduce by laying their eggs directly on or near water, people who live near bodies of water or wetlands are at the highest risk for mosquito bites. Patient factors that have been found to lead to increased rates of mosquito bites include lower microbial diversity on the skin, the presence of sweat or body odor, pregnancy, increased body temperature, type O blood, dark clothing, and perfumes.² Exaggerated bite reactions are associated with Epstein-Barr virus (EBV) infection and hematologic malignancies.¹⁰ 

Immediate hypersensitivity is mediated by a specific IgE antibody and is characterized by erythema and a wheal at the bite site that peaks within minutes of the bite. In contrast, delayed hypersensitivity is lymphocyte mediated; occurs 24 hours after the bite; and causes an indurated, pruritic, and erythematous 2- to 10-mm papule that may blister.¹¹ Although the evidence of immediate hypersensitivity disappears within hours, symptoms of delayed hypersensitivity may last days to weeks. Accompanying symptoms may include local swelling, pain, and warmth. The itch that often is experienced in conjunction with erythema and papule formation is elicited in 3 main ways: direct induction utilizing classic pruritic pathways, IgE-mediated hypersensitivity reaction to salivary components, and IgE-independent host immune response to salivary antigens. Papular urticaria is a common additional finding in children with mosquito bites.¹ As an individual is repeatedly bitten, they may undergo 5 stages of sensitization: stage I (neither immediate nor delayed reaction), stage II (delayed reaction), stage III (immediate and delayed reaction), stage IV (immediate reaction), and stage V (neither immediate or delayed reaction).¹¹

Although most mosquito bites cause common local reactions, patients rarely demonstrate systemic reactions that can be much more severe. Skeeter syndrome is a milder systemic response characterized by large local reactions (papules >30 mm in diameter) developing hours after a bite with accompanying fever.¹² The reaction typically peaks over days to weeks.² Although the reaction may resemble cellulitis clinically, a history of a preceding mosquito bite can help make the distinction.¹³ 

A more severe systemic reaction is HMB, which is characterized by intense local skin findings as well as generalized systemic symptoms. Initially, indurated, clear, or hemorrhagic bullae appear at the bite site (Figure 2). Later, there is progression to swelling, necrosis, and ulceration.¹⁰ Biopsies from the skin lesions associated with HMB reveal necrosis, interstitial and perivascular eosinophilic and lymphocytic infiltrates, and small vessels with fibrinoid necrosis.⁷ Systemically, high fever, general malaise, liver dysfunction, proteinuria, hematuria, hepatosplenomegaly, and lymph node enlargement may occur. Patients typically experience these severe symptoms each time they are bitten.¹⁰

The mechanism of the HMB reaction is complex but has a close association with natural killer (NK) cell lymphoproliferative disorder and EBV infection (Figure 3). In fact, it is not uncommon for HMB patients to develop malignant lymphomas during their clinical course, even those unrelated to EBV.¹⁴ Epstein-Barr virus, one of the human herpesviruses, produces latent infection in NK cells. It is hypothesized that after a mosquito bite, EBV may be reactivated within these cells by induced expression of the viral lytic-cycle transactivator gene BamHI Z fragment leftward open reading frame 1, BZLF1.⁶ In response to mosquito salivary gland components, CD4⁺ T cells proliferate and induce expression of the EBV oncogene latent membrane protein 1, LMP1, on NK cells, which then infiltrate the bite site.¹⁵ These EBV-infected NK cells also overexpress the Fas ligand, thus contributing to organ and tissue damage.⁶ In addition to activating oncogene expression on NK cells, T cells also activate the basophils and mast cells carrying mosquito-specific IgE, both of which also add to the severe skin reaction of HMB.¹⁵ The particular triad of HMB, chronic active EBV infection, and NK cell lymphoproliferative disorder commonly is known as HMB-EBV-NK or HEN disease.¹ Patients with HMB should be monitored for malignancy. The mortality of HMB is increased in patients in whom onset occurs when they are older than 9 years and with BZLF1 messenger RNA in skin lesions.⁶ 

Other rare reactions to mosquito bites include Wells syndrome, anaphylaxis, and superficial lymphangitis. Wells syndrome (also known as eosinophilic cellulitis) is characterized by erythematous or violaceous plaques and pruritic blisters. Although its etiology has not been defined, it is thought to be evoked or exacerbated by insect bites, with CD4⁺ T cells playing a primary role.¹ Anaphylaxis (angioedema, urticaria, and wheezing) rarely may occur due to mosquito salivary gland components but typically is caused by other stinging insects. Superficial lymphangitis, often misdiagnosed as an infection of the lymphatic system, presents within minutes as nontender pink streaks originating from the bite site. A biopsy with eosinophil and mast cell infiltrates consistent with an allergic-type reaction confirms the absence of infection. Patients respond well to glucocorticoid treatment.

Mosquitoes are vectors for many blood-borne diseases, including dengue hemorrhagic fever, malaria, Chikungunya virus, La Crosse encephalitis, St. Louis encephalitis, West Nile virus, and yellow fever.¹⁶ Additionally, scratching the bites may lead to superinfection and scarring.¹

Prevention and Treatment

Patients with known mosquito sensitivity should avoid areas of stagnant water and utilize preventative measures such as wearing protective clothing and using mosquito repellent containing DEET (N,N-diethyl-meta-toluamide), IR3535 (ethyl butylacetylaminopropionate), picaridin, or 2-undecanone (methyl nonyl ketone or IBI-246) when outdoors. Essential oils such as lemon, eucalyptus, citronella, and garlic are somewhat effective.¹ Additionally, prophylactic dosing of antihistamines may prevent milder reactions.

Although often supportive, treatment and management of mosquito bites depends on the extent of the reaction. For common local reactions, symptomatic management with topical anesthetics, calamine lotion, or corticosteroid creams is appropriate. If superinfection from scratching is a concern, antibiotics may be appropriate.

Management of more severe and systemic reactions such as HMB also is supportive, and the addition of oral corticosteroids to decrease inflammation is required.⁷ Severe HMB also has been treated with immunosuppressive and anticancer drugs, though the efficacy is limited. Venom immunotherapy is a preventative option for patients with mosquito-specific IgE antibodies, and hematopoietic stem cell transplant may be required in patients with HMB.^14,16

Conclusion

Mosquito allergens can cause a variety of reactions, ranging from those limited to the skin to those characterized by severe systemic effects. Although common local reactions can be symptomatically treated with topical medication, more severe reactions such as HMB require more involved clinical management. Hypersensitivity to mosquito bites is an important condition to recognize, as it is related to multiple organ impairment as well as later development of malignancy. Patients should be closely monitored during the entire clinical course and in the years following.

Incidence and Characteristics

Mosquitoes are insects categorized into the order of Diptera and family of Culicidae, and more than 3500 different species have been identified.¹ In the United States, the most common genus of mosquitoes is Aedes, with other common genera including Culex, Anopheles, Culiseta, and Coquillettidia. Most bites are performed by female rather than male mosquitoes, as it serves to complete their life cycle (Figure 1).¹

There are a variety of possible reactions to mosquito bites. Severe local reactions that are large (papules >30 mm in diameter) or are accompanied by systemic manifestations are referred to as hypersensitivity to mosquito bites (HMB).² These hypersensitivity reactions vary according to multiple factors, including comorbid conditions, genetic predisposition, and geographic location. The majority of the world’s population will exhibit local reactions to mosquito bites at some point during life, with the median age of onset of the first bite at 2 years of age.³ In a study by Arias-Cruz et al,⁴ the incidence of patient-reported large local reactions was 2.5%. Hypersensitivity to mosquito bites, perhaps the most rare reaction, is more common among Asian and Central American children.⁵ The median age of diagnosis for HMB is 7 years, and most reactions occur during the first 2 decades of life.^6,7

Clinical Presentation

Mosquitoes bite vertebrates in an attempt to feed and thus must locate the host’s blood vessels through a process known as probing, which often necessitates changing the bite site several times. Once the vessel is located and lacerated, the mosquito feeds either from the vessel directly or the hematoma around it. Not only does the bite cause trauma to the skin, but a cutaneous reaction also may occur in response to salivary gland secretions that concurrently are deposited in the host tissue.⁸ Mosquitoes’ salivary gland components are the primary cause of cutaneous reactions, as one study showed that bites from mosquitoes lacking salivary gland ducts were not associated with these reactions.⁹ Mosquito saliva contains a large number of compounds with biologic activities, including lysozymes, antibacterial glucosidases, anticoagulants, antiplatelet aggregating factors, and vasodilators, as well as a potentially large number of unknown allergenic proteins. As of 2016, 70 mosquito-derived allergens have been identified, but this number continues to grow.² After a bite from a mosquito, these compounds may result in host sensitization over time, though interestingly, sensitization to mosquito bites from a species different from the original offender does not occur due to lack of cross-reactivity between species.¹ 

Because mosquitoes reproduce by laying their eggs directly on or near water, people who live near bodies of water or wetlands are at the highest risk for mosquito bites. Patient factors that have been found to lead to increased rates of mosquito bites include lower microbial diversity on the skin, the presence of sweat or body odor, pregnancy, increased body temperature, type O blood, dark clothing, and perfumes.² Exaggerated bite reactions are associated with Epstein-Barr virus (EBV) infection and hematologic malignancies.¹⁰ 

Immediate hypersensitivity is mediated by a specific IgE antibody and is characterized by erythema and a wheal at the bite site that peaks within minutes of the bite. In contrast, delayed hypersensitivity is lymphocyte mediated; occurs 24 hours after the bite; and causes an indurated, pruritic, and erythematous 2- to 10-mm papule that may blister.¹¹ Although the evidence of immediate hypersensitivity disappears within hours, symptoms of delayed hypersensitivity may last days to weeks. Accompanying symptoms may include local swelling, pain, and warmth. The itch that often is experienced in conjunction with erythema and papule formation is elicited in 3 main ways: direct induction utilizing classic pruritic pathways, IgE-mediated hypersensitivity reaction to salivary components, and IgE-independent host immune response to salivary antigens. Papular urticaria is a common additional finding in children with mosquito bites.¹ As an individual is repeatedly bitten, they may undergo 5 stages of sensitization: stage I (neither immediate nor delayed reaction), stage II (delayed reaction), stage III (immediate and delayed reaction), stage IV (immediate reaction), and stage V (neither immediate or delayed reaction).¹¹

Although most mosquito bites cause common local reactions, patients rarely demonstrate systemic reactions that can be much more severe. Skeeter syndrome is a milder systemic response characterized by large local reactions (papules >30 mm in diameter) developing hours after a bite with accompanying fever.¹² The reaction typically peaks over days to weeks.² Although the reaction may resemble cellulitis clinically, a history of a preceding mosquito bite can help make the distinction.¹³ 

A more severe systemic reaction is HMB, which is characterized by intense local skin findings as well as generalized systemic symptoms. Initially, indurated, clear, or hemorrhagic bullae appear at the bite site (Figure 2). Later, there is progression to swelling, necrosis, and ulceration.¹⁰ Biopsies from the skin lesions associated with HMB reveal necrosis, interstitial and perivascular eosinophilic and lymphocytic infiltrates, and small vessels with fibrinoid necrosis.⁷ Systemically, high fever, general malaise, liver dysfunction, proteinuria, hematuria, hepatosplenomegaly, and lymph node enlargement may occur. Patients typically experience these severe symptoms each time they are bitten.¹⁰

The mechanism of the HMB reaction is complex but has a close association with natural killer (NK) cell lymphoproliferative disorder and EBV infection (Figure 3). In fact, it is not uncommon for HMB patients to develop malignant lymphomas during their clinical course, even those unrelated to EBV.¹⁴ Epstein-Barr virus, one of the human herpesviruses, produces latent infection in NK cells. It is hypothesized that after a mosquito bite, EBV may be reactivated within these cells by induced expression of the viral lytic-cycle transactivator gene BamHI Z fragment leftward open reading frame 1, BZLF1.⁶ In response to mosquito salivary gland components, CD4⁺ T cells proliferate and induce expression of the EBV oncogene latent membrane protein 1, LMP1, on NK cells, which then infiltrate the bite site.¹⁵ These EBV-infected NK cells also overexpress the Fas ligand, thus contributing to organ and tissue damage.⁶ In addition to activating oncogene expression on NK cells, T cells also activate the basophils and mast cells carrying mosquito-specific IgE, both of which also add to the severe skin reaction of HMB.¹⁵ The particular triad of HMB, chronic active EBV infection, and NK cell lymphoproliferative disorder commonly is known as HMB-EBV-NK or HEN disease.¹ Patients with HMB should be monitored for malignancy. The mortality of HMB is increased in patients in whom onset occurs when they are older than 9 years and with BZLF1 messenger RNA in skin lesions.⁶ 

Other rare reactions to mosquito bites include Wells syndrome, anaphylaxis, and superficial lymphangitis. Wells syndrome (also known as eosinophilic cellulitis) is characterized by erythematous or violaceous plaques and pruritic blisters. Although its etiology has not been defined, it is thought to be evoked or exacerbated by insect bites, with CD4⁺ T cells playing a primary role.¹ Anaphylaxis (angioedema, urticaria, and wheezing) rarely may occur due to mosquito salivary gland components but typically is caused by other stinging insects. Superficial lymphangitis, often misdiagnosed as an infection of the lymphatic system, presents within minutes as nontender pink streaks originating from the bite site. A biopsy with eosinophil and mast cell infiltrates consistent with an allergic-type reaction confirms the absence of infection. Patients respond well to glucocorticoid treatment.

Mosquitoes are vectors for many blood-borne diseases, including dengue hemorrhagic fever, malaria, Chikungunya virus, La Crosse encephalitis, St. Louis encephalitis, West Nile virus, and yellow fever.¹⁶ Additionally, scratching the bites may lead to superinfection and scarring.¹

Prevention and Treatment

Patients with known mosquito sensitivity should avoid areas of stagnant water and utilize preventative measures such as wearing protective clothing and using mosquito repellent containing DEET (N,N-diethyl-meta-toluamide), IR3535 (ethyl butylacetylaminopropionate), picaridin, or 2-undecanone (methyl nonyl ketone or IBI-246) when outdoors. Essential oils such as lemon, eucalyptus, citronella, and garlic are somewhat effective.¹ Additionally, prophylactic dosing of antihistamines may prevent milder reactions.

Although often supportive, treatment and management of mosquito bites depends on the extent of the reaction. For common local reactions, symptomatic management with topical anesthetics, calamine lotion, or corticosteroid creams is appropriate. If superinfection from scratching is a concern, antibiotics may be appropriate.

Management of more severe and systemic reactions such as HMB also is supportive, and the addition of oral corticosteroids to decrease inflammation is required.⁷ Severe HMB also has been treated with immunosuppressive and anticancer drugs, though the efficacy is limited. Venom immunotherapy is a preventative option for patients with mosquito-specific IgE antibodies, and hematopoietic stem cell transplant may be required in patients with HMB.^14,16

Conclusion

Mosquito allergens can cause a variety of reactions, ranging from those limited to the skin to those characterized by severe systemic effects. Although common local reactions can be symptomatically treated with topical medication, more severe reactions such as HMB require more involved clinical management. Hypersensitivity to mosquito bites is an important condition to recognize, as it is related to multiple organ impairment as well as later development of malignancy. Patients should be closely monitored during the entire clinical course and in the years following.

Jellyfish stings are one of the most common marine injuries, with an estimated 150 million stings occurring annually worldwide.¹ Most jellyfish stings result in painful localized skin reactions that are self-limited and can be treated with conservative measures including hot water immersion and topical anesthetics. Life-threatening systemic reactions (eg, anaphylaxis, Irukandji syndrome) can occur with some species.^2-4 Mainstream media reports do not reflect the true incidence and variability of jellyfish-related injuries that are commonly encountered in the clinic.³

Characteristics of Jellyfish

There are roughly 10,000 known species of jellyfish, with approximately 100 of them posing danger to humans.⁵ Jellyfish belong to the phylum Cnidaria, which is comprised of 5 classes of both free-floating and sessile animals: Staurozoa (stauromedusae), Hydrozoa (hydroids, fire corals, and Portuguese man-of-war), Scyphozoa (true jellyfish), Anthozoa (corals and sea anemones), and Cubozoa (box jellyfish and Irukandji jellyfish).^1,2,6 Jellyfish typically have several tentacles suspended from a free-floating gelatinous body or bell; these tentacles are covered with thousands of cells unique to Cnidaria called nematocytes or cnidocytes containing specialized stinging organelles known as nematocysts. When triggered by physical (eg, human or foreign-body contact) or chemical stimuli, each nematocyst ejects a hollow filament or barb externally, releasing venom into the victim.^7,8

The scyphozoan, hydrozoan, and cubozoan life cycles generally consist of a bottom-dwelling, sessile polyp form that produces multiple free-swimming ephyrae through an asexual reproductive process called strobilation. These ephyrae grow into the fully mature medusae, recognizable as jellyfish (Figure 1).⁵ Additionally, jellyfish populations experience cycles of temporal and spatial population abundance and crashes known as jellyfish blooms. In 2017, Kaffenberger et al⁹ reviewed the shifting landscape of skin diseases in North America attributable to major changes in climate and weather patterns, including the rise in jellyfish blooms and envenomation outbreaks worldwide (eg, Physalia physalis [Portuguese man-of-war][Figure 2] along the southeastern US coastline, Porpita pacifica off Japanese beaches). Some research suggests jellyfish surges relate to climate change and human interactions with jellyfish habitats by way of eutrophication and fishing (removing predators of jellyfish).^9,10

Clinical Presentation

Jellyfish injuries can vary greatly in clinical symptoms, but they do follow some basic patterns. The severity of pain and symptoms is related to the jellyfish species, the number of stinging cells (nematocysts) that are triggered, and the potency of the venom that is absorbed by the victim.^11-13 Most stings are minor, and patients experience immediate localized pain with serpiginous raised erythematous or urticarial lesions following the distribution of tentacle contact; these lesions have been described as tentaclelike and resembling a string of beads (Figure 3).¹² Pain usually lasts a couple hours, while the skin lesions can last hours to days and can even recur years later. This pattern fits that of the well-known hydrozoans P physalis and Physalia utriculus (bluebottle), which are endemic to the Atlantic and Indo-Pacific Oceans, respectively. The scyphozoan jellyfish causing similar presentations include Pelagia noctiluca (Mauve stinger), Aurelia aurita (Moon jellyfish), and Cyanea species. The cubozoan Chironex fleckeri (Australian box jellyfish or sea wasp) also causes tentaclelike stings but is widely considered the most dangerous jellyfish, as its venom is known to cause cardiac or respiratory arrest.^4,11 More than 100 fatalities have been reported following severe envenomations from C fleckeri in Australian and Indo-Pacific waters.⁶

Stings from another box jellyfish species, Carukia barnesi, cause a unique presentation known as Irukandji syndrome. Carukia barnesi is a small box jellyfish with a bell measuring roughly 2 cm in diameter. It has nematocysts on both its bell and tentacles. It inhabits deeper waters and typically stings divers but also can wash ashore and injure beach tourists. Although Irukandji syndrome usually is associated with C barnesi, which is endemic to Northern Australian beaches, other jellyfish species including P physalis rarely have been linked to this potentially fatal syndrome.^6,11 Unlike the immediate cutaneous and systemic findings described in C fleckeri encounters, symptoms of Irukandji-like stings can be delayed by up to 30 minutes. Patients may present with severe generalized pain (lower back, chest, headache), signs of excess catecholamine release (tachycardia, hypertension, anxiety, diaphoresis, agitation), or cardiopulmonary decompensation (arrhythmia, cardiac arrest, pulmonary edema).^6,11,14.15 Anaphylactic reactions also have been reported in those sensitized by prior stings.¹⁶

Management

Prevention of drowning is key in all marine injuries. Rescuers should remove the individual from the water, establish the ABCs—airway, breathing, and circulation—and seek acute medical attention. If immediate resuscitation is not required, douse the wound as soon as possible with a solution that halts further nematocyst discharge, which may contain alcohol, vinegar, or bicarbonate, depending on the prevalent species. General guidance is available to providers through evidence-based, point-of-care databases including UpToDate and DynaMed, as well as through the American Heart Association (AHA) or a country’s equivalent council on emergency care if residing outside the United States. Pressure immobilization bandages as a means of decreasing venom redistribution is no longer recommended by the AHA because animal studies have shown increased nematocyst discharge after pressure application.¹⁷ As such, touching or applying pressure to the affected area is not recommended until after a proper rinse solution has been applied. Tentacles may be removed mechanically with gloved hands or sand and seawater with minimal compression or agitation.

When acetic acid is appropriate, such as for cubozoan stings, commercially available vinegar (5% acetic acid in the United States) is preferred.^16,17 Tap water can cause discharge of nematocysts, and seawater is preferred when no other solution is available.¹⁸ Most marine venoms are heat labile. Immersion in hot water can produce pain relief, but ice can be just as efficacious and is preferred by some patients. Prior reports of patients stung by Physalia species demonstrated greater pain relief with hot water immersion compared to ice pack application.^18,19

In the setting of anaphylaxis, patients should receive epinephrine and be transported to a hospital with appropriate hemodynamic monitoring and supportive care. If the species of jellyfish has been identified, species-specific antivenin also may be available in certain regions (eg, C fleckeri antivenin manufactured in Australia), but it is unclear if it improves outcomes when compared with supportive care alone.^6,16

Conclusion

Following jellyfish stings, most skin lesions will spontaneously resolve. Patients likely will present days to weeks following the inciting event with mild cutaneous symptoms that are amenable to topical corticosteroids. Recurrent dermatitis following a jellyfish sting is uncommon and is thought to be due to an immunologic mechanism consistent with type IV hypersensitivity reactions. Patients may require multiple courses of treatment before complete resolution.²⁰

Patient education regarding marine envenomation and mechanical barriers such as wetsuits or stinger suits can reduce the risk for injury from jellyfish stings. Sting-inhibiting lotions also are commercially available, though more research is needed.²¹ Many beaches that are known to harbor the dangerous box jellyfish provide stinger nets to direct travelers to safer waters. Complete avoidance during jellyfish season is recommended in highly endemic areas.¹

Jellyfish stings are one of the most common marine injuries, with an estimated 150 million stings occurring annually worldwide.¹ Most jellyfish stings result in painful localized skin reactions that are self-limited and can be treated with conservative measures including hot water immersion and topical anesthetics. Life-threatening systemic reactions (eg, anaphylaxis, Irukandji syndrome) can occur with some species.^2-4 Mainstream media reports do not reflect the true incidence and variability of jellyfish-related injuries that are commonly encountered in the clinic.³

Characteristics of Jellyfish

There are roughly 10,000 known species of jellyfish, with approximately 100 of them posing danger to humans.⁵ Jellyfish belong to the phylum Cnidaria, which is comprised of 5 classes of both free-floating and sessile animals: Staurozoa (stauromedusae), Hydrozoa (hydroids, fire corals, and Portuguese man-of-war), Scyphozoa (true jellyfish), Anthozoa (corals and sea anemones), and Cubozoa (box jellyfish and Irukandji jellyfish).^1,2,6 Jellyfish typically have several tentacles suspended from a free-floating gelatinous body or bell; these tentacles are covered with thousands of cells unique to Cnidaria called nematocytes or cnidocytes containing specialized stinging organelles known as nematocysts. When triggered by physical (eg, human or foreign-body contact) or chemical stimuli, each nematocyst ejects a hollow filament or barb externally, releasing venom into the victim.^7,8

The scyphozoan, hydrozoan, and cubozoan life cycles generally consist of a bottom-dwelling, sessile polyp form that produces multiple free-swimming ephyrae through an asexual reproductive process called strobilation. These ephyrae grow into the fully mature medusae, recognizable as jellyfish (Figure 1).⁵ Additionally, jellyfish populations experience cycles of temporal and spatial population abundance and crashes known as jellyfish blooms. In 2017, Kaffenberger et al⁹ reviewed the shifting landscape of skin diseases in North America attributable to major changes in climate and weather patterns, including the rise in jellyfish blooms and envenomation outbreaks worldwide (eg, Physalia physalis [Portuguese man-of-war][Figure 2] along the southeastern US coastline, Porpita pacifica off Japanese beaches). Some research suggests jellyfish surges relate to climate change and human interactions with jellyfish habitats by way of eutrophication and fishing (removing predators of jellyfish).^9,10

Clinical Presentation

Jellyfish injuries can vary greatly in clinical symptoms, but they do follow some basic patterns. The severity of pain and symptoms is related to the jellyfish species, the number of stinging cells (nematocysts) that are triggered, and the potency of the venom that is absorbed by the victim.^11-13 Most stings are minor, and patients experience immediate localized pain with serpiginous raised erythematous or urticarial lesions following the distribution of tentacle contact; these lesions have been described as tentaclelike and resembling a string of beads (Figure 3).¹² Pain usually lasts a couple hours, while the skin lesions can last hours to days and can even recur years later. This pattern fits that of the well-known hydrozoans P physalis and Physalia utriculus (bluebottle), which are endemic to the Atlantic and Indo-Pacific Oceans, respectively. The scyphozoan jellyfish causing similar presentations include Pelagia noctiluca (Mauve stinger), Aurelia aurita (Moon jellyfish), and Cyanea species. The cubozoan Chironex fleckeri (Australian box jellyfish or sea wasp) also causes tentaclelike stings but is widely considered the most dangerous jellyfish, as its venom is known to cause cardiac or respiratory arrest.^4,11 More than 100 fatalities have been reported following severe envenomations from C fleckeri in Australian and Indo-Pacific waters.⁶

Stings from another box jellyfish species, Carukia barnesi, cause a unique presentation known as Irukandji syndrome. Carukia barnesi is a small box jellyfish with a bell measuring roughly 2 cm in diameter. It has nematocysts on both its bell and tentacles. It inhabits deeper waters and typically stings divers but also can wash ashore and injure beach tourists. Although Irukandji syndrome usually is associated with C barnesi, which is endemic to Northern Australian beaches, other jellyfish species including P physalis rarely have been linked to this potentially fatal syndrome.^6,11 Unlike the immediate cutaneous and systemic findings described in C fleckeri encounters, symptoms of Irukandji-like stings can be delayed by up to 30 minutes. Patients may present with severe generalized pain (lower back, chest, headache), signs of excess catecholamine release (tachycardia, hypertension, anxiety, diaphoresis, agitation), or cardiopulmonary decompensation (arrhythmia, cardiac arrest, pulmonary edema).^6,11,14.15 Anaphylactic reactions also have been reported in those sensitized by prior stings.¹⁶

Management

Prevention of drowning is key in all marine injuries. Rescuers should remove the individual from the water, establish the ABCs—airway, breathing, and circulation—and seek acute medical attention. If immediate resuscitation is not required, douse the wound as soon as possible with a solution that halts further nematocyst discharge, which may contain alcohol, vinegar, or bicarbonate, depending on the prevalent species. General guidance is available to providers through evidence-based, point-of-care databases including UpToDate and DynaMed, as well as through the American Heart Association (AHA) or a country’s equivalent council on emergency care if residing outside the United States. Pressure immobilization bandages as a means of decreasing venom redistribution is no longer recommended by the AHA because animal studies have shown increased nematocyst discharge after pressure application.¹⁷ As such, touching or applying pressure to the affected area is not recommended until after a proper rinse solution has been applied. Tentacles may be removed mechanically with gloved hands or sand and seawater with minimal compression or agitation.

When acetic acid is appropriate, such as for cubozoan stings, commercially available vinegar (5% acetic acid in the United States) is preferred.^16,17 Tap water can cause discharge of nematocysts, and seawater is preferred when no other solution is available.¹⁸ Most marine venoms are heat labile. Immersion in hot water can produce pain relief, but ice can be just as efficacious and is preferred by some patients. Prior reports of patients stung by Physalia species demonstrated greater pain relief with hot water immersion compared to ice pack application.^18,19

In the setting of anaphylaxis, patients should receive epinephrine and be transported to a hospital with appropriate hemodynamic monitoring and supportive care. If the species of jellyfish has been identified, species-specific antivenin also may be available in certain regions (eg, C fleckeri antivenin manufactured in Australia), but it is unclear if it improves outcomes when compared with supportive care alone.^6,16

Conclusion

Following jellyfish stings, most skin lesions will spontaneously resolve. Patients likely will present days to weeks following the inciting event with mild cutaneous symptoms that are amenable to topical corticosteroids. Recurrent dermatitis following a jellyfish sting is uncommon and is thought to be due to an immunologic mechanism consistent with type IV hypersensitivity reactions. Patients may require multiple courses of treatment before complete resolution.²⁰

Patient education regarding marine envenomation and mechanical barriers such as wetsuits or stinger suits can reduce the risk for injury from jellyfish stings. Sting-inhibiting lotions also are commercially available, though more research is needed.²¹ Many beaches that are known to harbor the dangerous box jellyfish provide stinger nets to direct travelers to safer waters. Complete avoidance during jellyfish season is recommended in highly endemic areas.¹

Jellyfish stings are one of the most common marine injuries, with an estimated 150 million stings occurring annually worldwide.¹ Most jellyfish stings result in painful localized skin reactions that are self-limited and can be treated with conservative measures including hot water immersion and topical anesthetics. Life-threatening systemic reactions (eg, anaphylaxis, Irukandji syndrome) can occur with some species.^2-4 Mainstream media reports do not reflect the true incidence and variability of jellyfish-related injuries that are commonly encountered in the clinic.³

Characteristics of Jellyfish

There are roughly 10,000 known species of jellyfish, with approximately 100 of them posing danger to humans.⁵ Jellyfish belong to the phylum Cnidaria, which is comprised of 5 classes of both free-floating and sessile animals: Staurozoa (stauromedusae), Hydrozoa (hydroids, fire corals, and Portuguese man-of-war), Scyphozoa (true jellyfish), Anthozoa (corals and sea anemones), and Cubozoa (box jellyfish and Irukandji jellyfish).^1,2,6 Jellyfish typically have several tentacles suspended from a free-floating gelatinous body or bell; these tentacles are covered with thousands of cells unique to Cnidaria called nematocytes or cnidocytes containing specialized stinging organelles known as nematocysts. When triggered by physical (eg, human or foreign-body contact) or chemical stimuli, each nematocyst ejects a hollow filament or barb externally, releasing venom into the victim.^7,8

The scyphozoan, hydrozoan, and cubozoan life cycles generally consist of a bottom-dwelling, sessile polyp form that produces multiple free-swimming ephyrae through an asexual reproductive process called strobilation. These ephyrae grow into the fully mature medusae, recognizable as jellyfish (Figure 1).⁵ Additionally, jellyfish populations experience cycles of temporal and spatial population abundance and crashes known as jellyfish blooms. In 2017, Kaffenberger et al⁹ reviewed the shifting landscape of skin diseases in North America attributable to major changes in climate and weather patterns, including the rise in jellyfish blooms and envenomation outbreaks worldwide (eg, Physalia physalis [Portuguese man-of-war][Figure 2] along the southeastern US coastline, Porpita pacifica off Japanese beaches). Some research suggests jellyfish surges relate to climate change and human interactions with jellyfish habitats by way of eutrophication and fishing (removing predators of jellyfish).^9,10

Clinical Presentation

Jellyfish injuries can vary greatly in clinical symptoms, but they do follow some basic patterns. The severity of pain and symptoms is related to the jellyfish species, the number of stinging cells (nematocysts) that are triggered, and the potency of the venom that is absorbed by the victim.^11-13 Most stings are minor, and patients experience immediate localized pain with serpiginous raised erythematous or urticarial lesions following the distribution of tentacle contact; these lesions have been described as tentaclelike and resembling a string of beads (Figure 3).¹² Pain usually lasts a couple hours, while the skin lesions can last hours to days and can even recur years later. This pattern fits that of the well-known hydrozoans P physalis and Physalia utriculus (bluebottle), which are endemic to the Atlantic and Indo-Pacific Oceans, respectively. The scyphozoan jellyfish causing similar presentations include Pelagia noctiluca (Mauve stinger), Aurelia aurita (Moon jellyfish), and Cyanea species. The cubozoan Chironex fleckeri (Australian box jellyfish or sea wasp) also causes tentaclelike stings but is widely considered the most dangerous jellyfish, as its venom is known to cause cardiac or respiratory arrest.^4,11 More than 100 fatalities have been reported following severe envenomations from C fleckeri in Australian and Indo-Pacific waters.⁶

Stings from another box jellyfish species, Carukia barnesi, cause a unique presentation known as Irukandji syndrome. Carukia barnesi is a small box jellyfish with a bell measuring roughly 2 cm in diameter. It has nematocysts on both its bell and tentacles. It inhabits deeper waters and typically stings divers but also can wash ashore and injure beach tourists. Although Irukandji syndrome usually is associated with C barnesi, which is endemic to Northern Australian beaches, other jellyfish species including P physalis rarely have been linked to this potentially fatal syndrome.^6,11 Unlike the immediate cutaneous and systemic findings described in C fleckeri encounters, symptoms of Irukandji-like stings can be delayed by up to 30 minutes. Patients may present with severe generalized pain (lower back, chest, headache), signs of excess catecholamine release (tachycardia, hypertension, anxiety, diaphoresis, agitation), or cardiopulmonary decompensation (arrhythmia, cardiac arrest, pulmonary edema).^6,11,14.15 Anaphylactic reactions also have been reported in those sensitized by prior stings.¹⁶

Management

Prevention of drowning is key in all marine injuries. Rescuers should remove the individual from the water, establish the ABCs—airway, breathing, and circulation—and seek acute medical attention. If immediate resuscitation is not required, douse the wound as soon as possible with a solution that halts further nematocyst discharge, which may contain alcohol, vinegar, or bicarbonate, depending on the prevalent species. General guidance is available to providers through evidence-based, point-of-care databases including UpToDate and DynaMed, as well as through the American Heart Association (AHA) or a country’s equivalent council on emergency care if residing outside the United States. Pressure immobilization bandages as a means of decreasing venom redistribution is no longer recommended by the AHA because animal studies have shown increased nematocyst discharge after pressure application.¹⁷ As such, touching or applying pressure to the affected area is not recommended until after a proper rinse solution has been applied. Tentacles may be removed mechanically with gloved hands or sand and seawater with minimal compression or agitation.

When acetic acid is appropriate, such as for cubozoan stings, commercially available vinegar (5% acetic acid in the United States) is preferred.^16,17 Tap water can cause discharge of nematocysts, and seawater is preferred when no other solution is available.¹⁸ Most marine venoms are heat labile. Immersion in hot water can produce pain relief, but ice can be just as efficacious and is preferred by some patients. Prior reports of patients stung by Physalia species demonstrated greater pain relief with hot water immersion compared to ice pack application.^18,19

In the setting of anaphylaxis, patients should receive epinephrine and be transported to a hospital with appropriate hemodynamic monitoring and supportive care. If the species of jellyfish has been identified, species-specific antivenin also may be available in certain regions (eg, C fleckeri antivenin manufactured in Australia), but it is unclear if it improves outcomes when compared with supportive care alone.^6,16

Conclusion

Following jellyfish stings, most skin lesions will spontaneously resolve. Patients likely will present days to weeks following the inciting event with mild cutaneous symptoms that are amenable to topical corticosteroids. Recurrent dermatitis following a jellyfish sting is uncommon and is thought to be due to an immunologic mechanism consistent with type IV hypersensitivity reactions. Patients may require multiple courses of treatment before complete resolution.²⁰

Patient education regarding marine envenomation and mechanical barriers such as wetsuits or stinger suits can reduce the risk for injury from jellyfish stings. Sting-inhibiting lotions also are commercially available, though more research is needed.²¹ Many beaches that are known to harbor the dangerous box jellyfish provide stinger nets to direct travelers to safer waters. Complete avoidance during jellyfish season is recommended in highly endemic areas.¹

Causes of Lepidopterism

Caterpillars are wormlike organisms that serve as the larval stage of moths and butterflies, which belong to the order Lepidoptera. There are almost 165,000 discovered species, with 13,000 found in the United States.^1,2 Roughly 150 species are known to have the potential to cause an adverse reaction in humans, with 50 of these in the United States.¹Lepidopterism describes systemic and cutaneous reactions to moths, butterflies, and caterpillars; erucism describes strictly cutaneous reactions.¹

Although the rate of lepidopterism is thought to be underreported because it often is self-limited and of a mild nature, a review found caterpillars to be the cause of roughly 2.2% of reported bites and stings annually.² Cases increase in number with seasonal increases in caterpillars, which vary by region and species. For example, the Megalopyge opercularis (southern flannel moth) caterpillar was noted to have 2 peaks in a Texas-based study: 12% of reported stings occurred in July; 59% from October through November.³ In general, the likelihood of exposure increases during warmer months, and exposure is more common in people who work outdoors in a rural area or in a suburban area where there are many caterpillar-infested trees.⁴

Most cases of lepidopterism are caused by caterpillars, not by adult butterflies and moths, because the former have many tubular, or porous, hairlike structures called setae that are embedded in the integument. Setae were once thought to be connected to poison-secreting glandular cells, but current belief is that venomous caterpillars lack specialized gland cells and instead produce venom through secretory epithelial cells located above the integument.¹ Venom accumulates in the hemolymph and is stored in the setae or other types of bristles, such as scoli (wartlike bumps that bear setae) or spines.⁵ With a large amount of chitin, bristles have a tendency to fracture and release venom upon contact.¹ It is thought that some species of caterpillars formulate venom by ingesting toxins or toxin precursors from plants; for example, the tiger moth (family Arctiidae) is known to produce venom containing biogenic amines, pyrrolizidine, alkaloids, and cardiac glycosides obtained through food sources.⁵

Even if a caterpillar does not produce venom, its setae might embed into skin or mucous membranes and cause an adverse irritant reaction.¹ Setae also might dislodge and be transported in the air to embed in objects—some remaining stable in the environment for longer than a year.² In contrast to setae, spines are permanently fixed into the integument; for that reason, only direct contact with the caterpillar can result in an adverse reaction. Although it is mostly caterpillars that contain setae and spines, certain species of moths also might contain these structures or might acquire them as they emerge from the cocoon, which often contains incorporated setae.²

Reactions in Humans

Lepidopterism encompasses 3 principal reactions in humans: sting reaction, hypersensitivity reaction, and lonomism (a hemorrhagic diathesis produced by Lonomia caterpillars). The type and severity of the reaction depends on (1) the species of caterpillar or moth and (2) the individual patient.² There are approximately 12 families of caterpillars, mainly of the moth variety, that can cause an adverse reaction in humans.¹ Tables 1 and 2 list examples of species that cause each type of reaction.⁶

Chemicals and toxins contained in the poison of setae and spines vary by species of caterpillar. Numerous kinds have been isolated from different venoms,^1,2 including several peptides, histamine, histamine-releasing substances, acetylcholine, phospholipase A, hyaluronidase, formic acid, proteins with trypsinlike activity, serine proteases such as kallikrein, and other enzymes with vasodegenerative and fibrinolytic properties

Stings: An Immediate Adverse Reaction—Depending on the venom, a sting might result in mild to severe burning pain, accompanied by welts, vesicles, and red papules or plaques.² Figure 1 demonstrates a particularly mild sting from a caterpillar of the family Automeris, examples of which are seen in Figures 2 and 3 and eFigure 1. Components of the venom determine the mechanism of the sting and the pain that accompanies it. For example, a recent study demonstrated that the venom of the Latoia consocia caterpillar induces pain through the ion-channel receptor known as transient receptor potential vanilloid 1, which integrates and sends painful stimuli from the peripheral nervous system to the central nervous system.⁷ It is thought that a variety of ion channels are targets of the venom of caterpillars.

One of the most characteristic sting patterns is that of the caterpillar of family Megalopygidae (flannel moth)(eFigures 2 and 3). The stings of these caterpillars create a unique tram-track pattern of hemorrhagic macules or papules (Figure 4).⁴ A study found that 90% of reported M opercularis envenomations consist primarily of cutaneous symptoms, with 84% of those symptoms being irritation or pain; 45% a puncture or wound; 29% erythema; and 15% edema.³ Systemic findings can include headache, fever, adenopathy, nausea, vomiting, abdominal pain, and chest pain.⁴ Symptoms normally are self-limited, though they can last minutes or hours.

Hypersensitivity Reaction—Studies demonstrate that the symptoms of this reaction are a mixture of type I hypersensitivity, type IV hypersensitivity, and a foreign-body response.² The specific hypersensitivity reaction depends on the venom and the exposed individual—most commonly including a combination of pruritic papules, urticarial wheals, flares, and dermatitis.² A reaction that is a result of direct contact with the caterpillar or moth will appear on exposed areas; however, because setae embed in linens and clothing, they might cause a reaction anywhere on the body. Although usually self-limited, a hypersensitivity reaction might develop within minutes and can last for days or weeks.

Stings and hypersensitivity reactions to caterpillars and moths tend to lead to a nonspecific histologic presentation characterized by epidermal edema and a superficial perivascular lymphocytic infiltrate, often with eosinophils.⁶ After approximately 1 week, a foreign-body response to setae can lead to tuberculoid granulomas accompanied by neutrophils in the dermis and occasionally in subcutaneous tissues (Figures 5 and 6).⁸ If setae have not yet been removed, they also might be visible in skin scrapings.

Additional complications can accompany the hypersensitivity reaction to setae or spines. Type I hypersensitivity reactions can lead to severe reactions on second contact due to previously sensitized IgE antibodies. Although the first reaction appears mild, second contact might result in angioedema, wheezing, dyspnea, or anaphylaxis, or a combination of these findings.⁹ In addition, some patients who come in contact with Dendrolimus caterpillars might develop a condition known as dendrolimiasis, characterized by dermatitis in addition to arthritis or chondritis.⁶ The arthritis is normally monoarticular and can result in complete destruction of the joint. Pararamose, a condition with a similar presentation, is caused by the Brazilian moth Premolis semirufa.⁶

Contact of setae or spines with mucous membranes or inhalation of setae also might result in edema, dysphagia, dyspnea, drooling, rhinitis, or conjunctivitis, or a combination of these findings.⁶ In addition, setae can embed in the eye and cause an inflammatory reaction—ophthalmia nodosa—most commonly caused by caterpillars of the pine processionary moth (Thaumetopoea pityocampa) and characterized by immediate chemosis, which can progress to liquefactive necrosis and hypopyon, later developing into a granulomatous foreign-body response.^2,10 The process is thought to be the result of a combination of the thaumetopoein toxin in the setae and an IgE-mediated response to other proteins.¹⁰

Due to their harpoon shape and forward-only motion, setae might migrate deeper, potentially even to the optic nerve.¹¹ Because migration might take years and the barbed shape of setae does not always allow removal, some patients require lifetime monitoring with slit-lamp examination.Chronic problems, such as cataracts and persistent posterior uveitis, have been reported.^10,11

Lonomism—One of the most serious (though rarest) reactions to caterpillars is lonomism, a condition caused by the caterpillars of Lonomia achelous and Lonomia obliqua moths. These caterpillars have a unique combination of toxins filling their branched spines, which ultimately leads to the same outcome: a hemorrhagic diathesis.

The toxin of L achelous comprises several proteases that degrade fibrin, fibrinogen, and factor XIII while activating prothrombin. In contrast, L obliqua poison causes a hemorrhagic diathesis by promoting a consumptive coagulopathy through enzymes that activate factor X and prothrombin.

With initial contact with either of these Lonomia caterpillars, the patient experiences severe pain accompanied by systemic symptoms, including headache, nausea, and vomiting. Shortly afterward, symptoms of a hemorrhagic diathesis manifest, including bleeding gums, hematuria, bleeding from prior wounds, and epistaxis.⁵ Serious complications of the hemorrhagic diathesis, such as hemorrhage of major organs, leads to death in 4% of patients.⁵ A reported case of a patient whose Lonomia caterpillar sting went unrecognized until a week after the accident ended with progression to stage V chronic renal disease.¹²

Recent research has focused on the specific mechanism of injury caused by Lonomia species. A study found that the venom of L obliqua causes cytoskeleton rearrangement and migration in vascular smooth muscle cells (VSMCs) by inducing formation of reactive oxygen species through activation of nicotinamide adenine dinucleotide phosphate oxidase.¹³ Thus, the venom directly contributes to the proinflammatory phenotype of endothelial cells seen following envenomation. The same study also demonstrated that elevated reactive oxygen species trigger extracellular signal-regulated kinase pathway activation in VSMCs, leading to cell proliferation, re-stenosis, and ischemia.¹³ This finding was confirmed by another study,¹⁴ which demonstrated an increase in Rac1, a signaling protein involved in the extracellular signal-regulated kinase pathway, in VSMCs upon exposure to L obliqua venom. These studies propose potential new targets for treatment to prevent vascular damage.

Reactions to Adult Organisms—Although it is more common for the caterpillar form of these organisms to cause an adverse reaction, the adult moth also might be capable of causing a similar reaction by retaining setae from the cocoon or by their own spines. The most notable example of this is female moths of the genus Hylesia, which possess spines attached to glands on the abdomen. The poison in these spines—a mixture of proteases and chitinase—causes a dermatitis known as Caripito itch—the name derived from a river port in Venezuela where this moth caused a memorable epidemic of moth-induced dermatitis.^7,15 Caripito itch is known for intense pruritus that most commonly lasts days or weeks, possibly longer than 1 year.

Diagnostic Difficulties

The challenge of diagnosing a caterpillar- or moth-induced reaction in humans arises from (1) the lack of clinical history (the caterpillar might not be seen at all by the patient or the examiner) and (2) the similarity of these reactions to those with more common triggers.

When setae remain embedded in the skin or mucous membranes, skin scrapings allow accelerated diagnosis. On a skin scraping prepared with 20% potassium hydroxide, setae appear as tapered and barbed hairlike structures, which allows them to be distinguished from other similar-appearing but differently shaped structures, such as glass fibers.

When setae do not remain embedded in the skin or when the cause of the reaction is due to spines, the physician is left with a nonspecific histologic picture and a large differential diagnosis to be narrowed down based on the history and occasionally the pattern of the skin lesion.

A challenge in sting diagnosis is differentiating a caterpillar or moth sting from that of another organism. In certain cases, such as those of the family Megalopygidae, specific patterns of stings might assist in making the diagnosis. Hypersensitivity reactions are associated with a wider differential diagnosis, including irritant or allergic dermatitis from other causes, scabies, eczema, lichen planus, lichen simplex chronicus, seborrheic dermatitis, and tinea corporis, to name a few.⁶ Skin scrapings can be examined for other features, such as burrows in the case of scabies, to further narrow the differential.

Stings and hypersensitivity reactions lacking a proper history and associated with more severe systemic symptoms have caused misdiagnosis or led to a workup for the wrong condition; for example, the picture of abdominal pain, nausea, vomiting, tachycardia, leukocytosis, hypokalemia, and metabolic acidosis can simulate appendicitis.¹⁶ Upon discovery of a puss caterpillar sting in a patient, her symptoms resolved after treatment with ondansetron, morphine, and intravenous fluids.¹⁶

In lonomism, the diagnosis must be established by laboratory measurement of the fibrinogen level, clotting factors, prothrombin time, and activated partial thromboplastin time.⁴ The differential diagnosis associated with lonomism includes disseminated intravascular coagulation (DIC), snakebite, and a hereditary bleeding disorder.⁴ The combination of laboratory tests and an extensive medical history allows a diagnosis. Absence of a personal or family history of bleeding excludes a diagnosis of hereditary bleeding disorder, whereas the absence of known causes of DIC or thrombocytopenia allows DIC to be excluded from the differential.

Treatment Options and Prevention

Treatment—The first step is to remove any embedded setae from the skin or mucous membranes. The stepwise recommendation is to remove any constricted clothing, detach setae with adhesive tape, wash with soap and water, and dry without touching the skin.¹ Any remaining setae can be removed with additional tape or forceps; setae tend to be fragile and are difficult to remove in their entirety.

Other than removal of the setae, skin reactions are treated symptomatically. Ice packs and isopropyl alcohol have been utilized to cool burning or stinging areas. Pain, pruritus, and inflammation have been alleviated with antihistamines and topical corticosteroids.¹ When pain is severe, oral codeine or local injection of anesthetic can be used. For severe and persistent skin lesions, a course of an oral glucocorticoid can be administered. Intramuscular triamcinolone acetonide has been shown to treat pain, dermatitis, and subcutaneous nodules otherwise refractory to treatment.⁸

Antivenin specific for L obliqua exists to treat lonomism and is therefore effective only when lonomism is caused by that species. Lonomism caused by L achelous is treated with cryoprecipitate, purified fibrinogen, and antifibrinolytic drugs, such as aprotinin.⁶ Whole blood and fresh-frozen plasma have been noted to make hemorrhage worse when utilized to treat lonomism. Because the mechanism of action of the venom of Lonomia species is based, in part, on inducing a proinflammatory profile in endothelial cells, studies have demonstrated that inhibition of kallikrein might prevent vascular injury and thus prevent serious adverse effects, such as renal failure.¹⁷

Prevention—People should wear proper protective clothing when outdoors in potentially infested areas. Measures should be taken to ensure that linens and clothing are not left outside in areas where setae might be carried on the wind. Infestation control is necessary if the population of caterpillars reaches a high enough level.

Conclusion

Several species of caterpillars and moths cause adverse reactions in humans: stings, hypersensitivity reactions, and lonomism. Although most reactions are self-limited, some might have more serious effects, including organ failure and death. Mechanisms of injury vary by species of caterpillar, moth, and butterfly; current research is focused on further defining venom components and signaling pathways to isolate potential targets to aid in the diagnosis and treatment of lepidopterism.

Causes of Lepidopterism

Caterpillars are wormlike organisms that serve as the larval stage of moths and butterflies, which belong to the order Lepidoptera. There are almost 165,000 discovered species, with 13,000 found in the United States.^1,2 Roughly 150 species are known to have the potential to cause an adverse reaction in humans, with 50 of these in the United States.¹Lepidopterism describes systemic and cutaneous reactions to moths, butterflies, and caterpillars; erucism describes strictly cutaneous reactions.¹

Although the rate of lepidopterism is thought to be underreported because it often is self-limited and of a mild nature, a review found caterpillars to be the cause of roughly 2.2% of reported bites and stings annually.² Cases increase in number with seasonal increases in caterpillars, which vary by region and species. For example, the Megalopyge opercularis (southern flannel moth) caterpillar was noted to have 2 peaks in a Texas-based study: 12% of reported stings occurred in July; 59% from October through November.³ In general, the likelihood of exposure increases during warmer months, and exposure is more common in people who work outdoors in a rural area or in a suburban area where there are many caterpillar-infested trees.⁴

Most cases of lepidopterism are caused by caterpillars, not by adult butterflies and moths, because the former have many tubular, or porous, hairlike structures called setae that are embedded in the integument. Setae were once thought to be connected to poison-secreting glandular cells, but current belief is that venomous caterpillars lack specialized gland cells and instead produce venom through secretory epithelial cells located above the integument.¹ Venom accumulates in the hemolymph and is stored in the setae or other types of bristles, such as scoli (wartlike bumps that bear setae) or spines.⁵ With a large amount of chitin, bristles have a tendency to fracture and release venom upon contact.¹ It is thought that some species of caterpillars formulate venom by ingesting toxins or toxin precursors from plants; for example, the tiger moth (family Arctiidae) is known to produce venom containing biogenic amines, pyrrolizidine, alkaloids, and cardiac glycosides obtained through food sources.⁵

Even if a caterpillar does not produce venom, its setae might embed into skin or mucous membranes and cause an adverse irritant reaction.¹ Setae also might dislodge and be transported in the air to embed in objects—some remaining stable in the environment for longer than a year.² In contrast to setae, spines are permanently fixed into the integument; for that reason, only direct contact with the caterpillar can result in an adverse reaction. Although it is mostly caterpillars that contain setae and spines, certain species of moths also might contain these structures or might acquire them as they emerge from the cocoon, which often contains incorporated setae.²

Reactions in Humans

Lepidopterism encompasses 3 principal reactions in humans: sting reaction, hypersensitivity reaction, and lonomism (a hemorrhagic diathesis produced by Lonomia caterpillars). The type and severity of the reaction depends on (1) the species of caterpillar or moth and (2) the individual patient.² There are approximately 12 families of caterpillars, mainly of the moth variety, that can cause an adverse reaction in humans.¹ Tables 1 and 2 list examples of species that cause each type of reaction.⁶

Chemicals and toxins contained in the poison of setae and spines vary by species of caterpillar. Numerous kinds have been isolated from different venoms,^1,2 including several peptides, histamine, histamine-releasing substances, acetylcholine, phospholipase A, hyaluronidase, formic acid, proteins with trypsinlike activity, serine proteases such as kallikrein, and other enzymes with vasodegenerative and fibrinolytic properties

Stings: An Immediate Adverse Reaction—Depending on the venom, a sting might result in mild to severe burning pain, accompanied by welts, vesicles, and red papules or plaques.² Figure 1 demonstrates a particularly mild sting from a caterpillar of the family Automeris, examples of which are seen in Figures 2 and 3 and eFigure 1. Components of the venom determine the mechanism of the sting and the pain that accompanies it. For example, a recent study demonstrated that the venom of the Latoia consocia caterpillar induces pain through the ion-channel receptor known as transient receptor potential vanilloid 1, which integrates and sends painful stimuli from the peripheral nervous system to the central nervous system.⁷ It is thought that a variety of ion channels are targets of the venom of caterpillars.

One of the most characteristic sting patterns is that of the caterpillar of family Megalopygidae (flannel moth)(eFigures 2 and 3). The stings of these caterpillars create a unique tram-track pattern of hemorrhagic macules or papules (Figure 4).⁴ A study found that 90% of reported M opercularis envenomations consist primarily of cutaneous symptoms, with 84% of those symptoms being irritation or pain; 45% a puncture or wound; 29% erythema; and 15% edema.³ Systemic findings can include headache, fever, adenopathy, nausea, vomiting, abdominal pain, and chest pain.⁴ Symptoms normally are self-limited, though they can last minutes or hours.

Hypersensitivity Reaction—Studies demonstrate that the symptoms of this reaction are a mixture of type I hypersensitivity, type IV hypersensitivity, and a foreign-body response.² The specific hypersensitivity reaction depends on the venom and the exposed individual—most commonly including a combination of pruritic papules, urticarial wheals, flares, and dermatitis.² A reaction that is a result of direct contact with the caterpillar or moth will appear on exposed areas; however, because setae embed in linens and clothing, they might cause a reaction anywhere on the body. Although usually self-limited, a hypersensitivity reaction might develop within minutes and can last for days or weeks.

Stings and hypersensitivity reactions to caterpillars and moths tend to lead to a nonspecific histologic presentation characterized by epidermal edema and a superficial perivascular lymphocytic infiltrate, often with eosinophils.⁶ After approximately 1 week, a foreign-body response to setae can lead to tuberculoid granulomas accompanied by neutrophils in the dermis and occasionally in subcutaneous tissues (Figures 5 and 6).⁸ If setae have not yet been removed, they also might be visible in skin scrapings.

Additional complications can accompany the hypersensitivity reaction to setae or spines. Type I hypersensitivity reactions can lead to severe reactions on second contact due to previously sensitized IgE antibodies. Although the first reaction appears mild, second contact might result in angioedema, wheezing, dyspnea, or anaphylaxis, or a combination of these findings.⁹ In addition, some patients who come in contact with Dendrolimus caterpillars might develop a condition known as dendrolimiasis, characterized by dermatitis in addition to arthritis or chondritis.⁶ The arthritis is normally monoarticular and can result in complete destruction of the joint. Pararamose, a condition with a similar presentation, is caused by the Brazilian moth Premolis semirufa.⁶

Contact of setae or spines with mucous membranes or inhalation of setae also might result in edema, dysphagia, dyspnea, drooling, rhinitis, or conjunctivitis, or a combination of these findings.⁶ In addition, setae can embed in the eye and cause an inflammatory reaction—ophthalmia nodosa—most commonly caused by caterpillars of the pine processionary moth (Thaumetopoea pityocampa) and characterized by immediate chemosis, which can progress to liquefactive necrosis and hypopyon, later developing into a granulomatous foreign-body response.^2,10 The process is thought to be the result of a combination of the thaumetopoein toxin in the setae and an IgE-mediated response to other proteins.¹⁰

Due to their harpoon shape and forward-only motion, setae might migrate deeper, potentially even to the optic nerve.¹¹ Because migration might take years and the barbed shape of setae does not always allow removal, some patients require lifetime monitoring with slit-lamp examination.Chronic problems, such as cataracts and persistent posterior uveitis, have been reported.^10,11

Lonomism—One of the most serious (though rarest) reactions to caterpillars is lonomism, a condition caused by the caterpillars of Lonomia achelous and Lonomia obliqua moths. These caterpillars have a unique combination of toxins filling their branched spines, which ultimately leads to the same outcome: a hemorrhagic diathesis.

The toxin of L achelous comprises several proteases that degrade fibrin, fibrinogen, and factor XIII while activating prothrombin. In contrast, L obliqua poison causes a hemorrhagic diathesis by promoting a consumptive coagulopathy through enzymes that activate factor X and prothrombin.

With initial contact with either of these Lonomia caterpillars, the patient experiences severe pain accompanied by systemic symptoms, including headache, nausea, and vomiting. Shortly afterward, symptoms of a hemorrhagic diathesis manifest, including bleeding gums, hematuria, bleeding from prior wounds, and epistaxis.⁵ Serious complications of the hemorrhagic diathesis, such as hemorrhage of major organs, leads to death in 4% of patients.⁵ A reported case of a patient whose Lonomia caterpillar sting went unrecognized until a week after the accident ended with progression to stage V chronic renal disease.¹²

Recent research has focused on the specific mechanism of injury caused by Lonomia species. A study found that the venom of L obliqua causes cytoskeleton rearrangement and migration in vascular smooth muscle cells (VSMCs) by inducing formation of reactive oxygen species through activation of nicotinamide adenine dinucleotide phosphate oxidase.¹³ Thus, the venom directly contributes to the proinflammatory phenotype of endothelial cells seen following envenomation. The same study also demonstrated that elevated reactive oxygen species trigger extracellular signal-regulated kinase pathway activation in VSMCs, leading to cell proliferation, re-stenosis, and ischemia.¹³ This finding was confirmed by another study,¹⁴ which demonstrated an increase in Rac1, a signaling protein involved in the extracellular signal-regulated kinase pathway, in VSMCs upon exposure to L obliqua venom. These studies propose potential new targets for treatment to prevent vascular damage.

Reactions to Adult Organisms—Although it is more common for the caterpillar form of these organisms to cause an adverse reaction, the adult moth also might be capable of causing a similar reaction by retaining setae from the cocoon or by their own spines. The most notable example of this is female moths of the genus Hylesia, which possess spines attached to glands on the abdomen. The poison in these spines—a mixture of proteases and chitinase—causes a dermatitis known as Caripito itch—the name derived from a river port in Venezuela where this moth caused a memorable epidemic of moth-induced dermatitis.^7,15 Caripito itch is known for intense pruritus that most commonly lasts days or weeks, possibly longer than 1 year.

Diagnostic Difficulties

The challenge of diagnosing a caterpillar- or moth-induced reaction in humans arises from (1) the lack of clinical history (the caterpillar might not be seen at all by the patient or the examiner) and (2) the similarity of these reactions to those with more common triggers.

When setae remain embedded in the skin or mucous membranes, skin scrapings allow accelerated diagnosis. On a skin scraping prepared with 20% potassium hydroxide, setae appear as tapered and barbed hairlike structures, which allows them to be distinguished from other similar-appearing but differently shaped structures, such as glass fibers.

When setae do not remain embedded in the skin or when the cause of the reaction is due to spines, the physician is left with a nonspecific histologic picture and a large differential diagnosis to be narrowed down based on the history and occasionally the pattern of the skin lesion.

A challenge in sting diagnosis is differentiating a caterpillar or moth sting from that of another organism. In certain cases, such as those of the family Megalopygidae, specific patterns of stings might assist in making the diagnosis. Hypersensitivity reactions are associated with a wider differential diagnosis, including irritant or allergic dermatitis from other causes, scabies, eczema, lichen planus, lichen simplex chronicus, seborrheic dermatitis, and tinea corporis, to name a few.⁶ Skin scrapings can be examined for other features, such as burrows in the case of scabies, to further narrow the differential.

Stings and hypersensitivity reactions lacking a proper history and associated with more severe systemic symptoms have caused misdiagnosis or led to a workup for the wrong condition; for example, the picture of abdominal pain, nausea, vomiting, tachycardia, leukocytosis, hypokalemia, and metabolic acidosis can simulate appendicitis.¹⁶ Upon discovery of a puss caterpillar sting in a patient, her symptoms resolved after treatment with ondansetron, morphine, and intravenous fluids.¹⁶

In lonomism, the diagnosis must be established by laboratory measurement of the fibrinogen level, clotting factors, prothrombin time, and activated partial thromboplastin time.⁴ The differential diagnosis associated with lonomism includes disseminated intravascular coagulation (DIC), snakebite, and a hereditary bleeding disorder.⁴ The combination of laboratory tests and an extensive medical history allows a diagnosis. Absence of a personal or family history of bleeding excludes a diagnosis of hereditary bleeding disorder, whereas the absence of known causes of DIC or thrombocytopenia allows DIC to be excluded from the differential.

Treatment Options and Prevention

Treatment—The first step is to remove any embedded setae from the skin or mucous membranes. The stepwise recommendation is to remove any constricted clothing, detach setae with adhesive tape, wash with soap and water, and dry without touching the skin.¹ Any remaining setae can be removed with additional tape or forceps; setae tend to be fragile and are difficult to remove in their entirety.

Other than removal of the setae, skin reactions are treated symptomatically. Ice packs and isopropyl alcohol have been utilized to cool burning or stinging areas. Pain, pruritus, and inflammation have been alleviated with antihistamines and topical corticosteroids.¹ When pain is severe, oral codeine or local injection of anesthetic can be used. For severe and persistent skin lesions, a course of an oral glucocorticoid can be administered. Intramuscular triamcinolone acetonide has been shown to treat pain, dermatitis, and subcutaneous nodules otherwise refractory to treatment.⁸

Antivenin specific for L obliqua exists to treat lonomism and is therefore effective only when lonomism is caused by that species. Lonomism caused by L achelous is treated with cryoprecipitate, purified fibrinogen, and antifibrinolytic drugs, such as aprotinin.⁶ Whole blood and fresh-frozen plasma have been noted to make hemorrhage worse when utilized to treat lonomism. Because the mechanism of action of the venom of Lonomia species is based, in part, on inducing a proinflammatory profile in endothelial cells, studies have demonstrated that inhibition of kallikrein might prevent vascular injury and thus prevent serious adverse effects, such as renal failure.¹⁷

Prevention—People should wear proper protective clothing when outdoors in potentially infested areas. Measures should be taken to ensure that linens and clothing are not left outside in areas where setae might be carried on the wind. Infestation control is necessary if the population of caterpillars reaches a high enough level.

Conclusion

Several species of caterpillars and moths cause adverse reactions in humans: stings, hypersensitivity reactions, and lonomism. Although most reactions are self-limited, some might have more serious effects, including organ failure and death. Mechanisms of injury vary by species of caterpillar, moth, and butterfly; current research is focused on further defining venom components and signaling pathways to isolate potential targets to aid in the diagnosis and treatment of lepidopterism.

Causes of Lepidopterism

Caterpillars are wormlike organisms that serve as the larval stage of moths and butterflies, which belong to the order Lepidoptera. There are almost 165,000 discovered species, with 13,000 found in the United States.^1,2 Roughly 150 species are known to have the potential to cause an adverse reaction in humans, with 50 of these in the United States.¹Lepidopterism describes systemic and cutaneous reactions to moths, butterflies, and caterpillars; erucism describes strictly cutaneous reactions.¹

Although the rate of lepidopterism is thought to be underreported because it often is self-limited and of a mild nature, a review found caterpillars to be the cause of roughly 2.2% of reported bites and stings annually.² Cases increase in number with seasonal increases in caterpillars, which vary by region and species. For example, the Megalopyge opercularis (southern flannel moth) caterpillar was noted to have 2 peaks in a Texas-based study: 12% of reported stings occurred in July; 59% from October through November.³ In general, the likelihood of exposure increases during warmer months, and exposure is more common in people who work outdoors in a rural area or in a suburban area where there are many caterpillar-infested trees.⁴

Most cases of lepidopterism are caused by caterpillars, not by adult butterflies and moths, because the former have many tubular, or porous, hairlike structures called setae that are embedded in the integument. Setae were once thought to be connected to poison-secreting glandular cells, but current belief is that venomous caterpillars lack specialized gland cells and instead produce venom through secretory epithelial cells located above the integument.¹ Venom accumulates in the hemolymph and is stored in the setae or other types of bristles, such as scoli (wartlike bumps that bear setae) or spines.⁵ With a large amount of chitin, bristles have a tendency to fracture and release venom upon contact.¹ It is thought that some species of caterpillars formulate venom by ingesting toxins or toxin precursors from plants; for example, the tiger moth (family Arctiidae) is known to produce venom containing biogenic amines, pyrrolizidine, alkaloids, and cardiac glycosides obtained through food sources.⁵

Even if a caterpillar does not produce venom, its setae might embed into skin or mucous membranes and cause an adverse irritant reaction.¹ Setae also might dislodge and be transported in the air to embed in objects—some remaining stable in the environment for longer than a year.² In contrast to setae, spines are permanently fixed into the integument; for that reason, only direct contact with the caterpillar can result in an adverse reaction. Although it is mostly caterpillars that contain setae and spines, certain species of moths also might contain these structures or might acquire them as they emerge from the cocoon, which often contains incorporated setae.²

Reactions in Humans

Lepidopterism encompasses 3 principal reactions in humans: sting reaction, hypersensitivity reaction, and lonomism (a hemorrhagic diathesis produced by Lonomia caterpillars). The type and severity of the reaction depends on (1) the species of caterpillar or moth and (2) the individual patient.² There are approximately 12 families of caterpillars, mainly of the moth variety, that can cause an adverse reaction in humans.¹ Tables 1 and 2 list examples of species that cause each type of reaction.⁶

Chemicals and toxins contained in the poison of setae and spines vary by species of caterpillar. Numerous kinds have been isolated from different venoms,^1,2 including several peptides, histamine, histamine-releasing substances, acetylcholine, phospholipase A, hyaluronidase, formic acid, proteins with trypsinlike activity, serine proteases such as kallikrein, and other enzymes with vasodegenerative and fibrinolytic properties

Stings: An Immediate Adverse Reaction—Depending on the venom, a sting might result in mild to severe burning pain, accompanied by welts, vesicles, and red papules or plaques.² Figure 1 demonstrates a particularly mild sting from a caterpillar of the family Automeris, examples of which are seen in Figures 2 and 3 and eFigure 1. Components of the venom determine the mechanism of the sting and the pain that accompanies it. For example, a recent study demonstrated that the venom of the Latoia consocia caterpillar induces pain through the ion-channel receptor known as transient receptor potential vanilloid 1, which integrates and sends painful stimuli from the peripheral nervous system to the central nervous system.⁷ It is thought that a variety of ion channels are targets of the venom of caterpillars.

One of the most characteristic sting patterns is that of the caterpillar of family Megalopygidae (flannel moth)(eFigures 2 and 3). The stings of these caterpillars create a unique tram-track pattern of hemorrhagic macules or papules (Figure 4).⁴ A study found that 90% of reported M opercularis envenomations consist primarily of cutaneous symptoms, with 84% of those symptoms being irritation or pain; 45% a puncture or wound; 29% erythema; and 15% edema.³ Systemic findings can include headache, fever, adenopathy, nausea, vomiting, abdominal pain, and chest pain.⁴ Symptoms normally are self-limited, though they can last minutes or hours.

Hypersensitivity Reaction—Studies demonstrate that the symptoms of this reaction are a mixture of type I hypersensitivity, type IV hypersensitivity, and a foreign-body response.² The specific hypersensitivity reaction depends on the venom and the exposed individual—most commonly including a combination of pruritic papules, urticarial wheals, flares, and dermatitis.² A reaction that is a result of direct contact with the caterpillar or moth will appear on exposed areas; however, because setae embed in linens and clothing, they might cause a reaction anywhere on the body. Although usually self-limited, a hypersensitivity reaction might develop within minutes and can last for days or weeks.

Stings and hypersensitivity reactions to caterpillars and moths tend to lead to a nonspecific histologic presentation characterized by epidermal edema and a superficial perivascular lymphocytic infiltrate, often with eosinophils.⁶ After approximately 1 week, a foreign-body response to setae can lead to tuberculoid granulomas accompanied by neutrophils in the dermis and occasionally in subcutaneous tissues (Figures 5 and 6).⁸ If setae have not yet been removed, they also might be visible in skin scrapings.

Additional complications can accompany the hypersensitivity reaction to setae or spines. Type I hypersensitivity reactions can lead to severe reactions on second contact due to previously sensitized IgE antibodies. Although the first reaction appears mild, second contact might result in angioedema, wheezing, dyspnea, or anaphylaxis, or a combination of these findings.⁹ In addition, some patients who come in contact with Dendrolimus caterpillars might develop a condition known as dendrolimiasis, characterized by dermatitis in addition to arthritis or chondritis.⁶ The arthritis is normally monoarticular and can result in complete destruction of the joint. Pararamose, a condition with a similar presentation, is caused by the Brazilian moth Premolis semirufa.⁶

Contact of setae or spines with mucous membranes or inhalation of setae also might result in edema, dysphagia, dyspnea, drooling, rhinitis, or conjunctivitis, or a combination of these findings.⁶ In addition, setae can embed in the eye and cause an inflammatory reaction—ophthalmia nodosa—most commonly caused by caterpillars of the pine processionary moth (Thaumetopoea pityocampa) and characterized by immediate chemosis, which can progress to liquefactive necrosis and hypopyon, later developing into a granulomatous foreign-body response.^2,10 The process is thought to be the result of a combination of the thaumetopoein toxin in the setae and an IgE-mediated response to other proteins.¹⁰

Due to their harpoon shape and forward-only motion, setae might migrate deeper, potentially even to the optic nerve.¹¹ Because migration might take years and the barbed shape of setae does not always allow removal, some patients require lifetime monitoring with slit-lamp examination.Chronic problems, such as cataracts and persistent posterior uveitis, have been reported.^10,11

Lonomism—One of the most serious (though rarest) reactions to caterpillars is lonomism, a condition caused by the caterpillars of Lonomia achelous and Lonomia obliqua moths. These caterpillars have a unique combination of toxins filling their branched spines, which ultimately leads to the same outcome: a hemorrhagic diathesis.

The toxin of L achelous comprises several proteases that degrade fibrin, fibrinogen, and factor XIII while activating prothrombin. In contrast, L obliqua poison causes a hemorrhagic diathesis by promoting a consumptive coagulopathy through enzymes that activate factor X and prothrombin.

With initial contact with either of these Lonomia caterpillars, the patient experiences severe pain accompanied by systemic symptoms, including headache, nausea, and vomiting. Shortly afterward, symptoms of a hemorrhagic diathesis manifest, including bleeding gums, hematuria, bleeding from prior wounds, and epistaxis.⁵ Serious complications of the hemorrhagic diathesis, such as hemorrhage of major organs, leads to death in 4% of patients.⁵ A reported case of a patient whose Lonomia caterpillar sting went unrecognized until a week after the accident ended with progression to stage V chronic renal disease.¹²

Recent research has focused on the specific mechanism of injury caused by Lonomia species. A study found that the venom of L obliqua causes cytoskeleton rearrangement and migration in vascular smooth muscle cells (VSMCs) by inducing formation of reactive oxygen species through activation of nicotinamide adenine dinucleotide phosphate oxidase.¹³ Thus, the venom directly contributes to the proinflammatory phenotype of endothelial cells seen following envenomation. The same study also demonstrated that elevated reactive oxygen species trigger extracellular signal-regulated kinase pathway activation in VSMCs, leading to cell proliferation, re-stenosis, and ischemia.¹³ This finding was confirmed by another study,¹⁴ which demonstrated an increase in Rac1, a signaling protein involved in the extracellular signal-regulated kinase pathway, in VSMCs upon exposure to L obliqua venom. These studies propose potential new targets for treatment to prevent vascular damage.

Reactions to Adult Organisms—Although it is more common for the caterpillar form of these organisms to cause an adverse reaction, the adult moth also might be capable of causing a similar reaction by retaining setae from the cocoon or by their own spines. The most notable example of this is female moths of the genus Hylesia, which possess spines attached to glands on the abdomen. The poison in these spines—a mixture of proteases and chitinase—causes a dermatitis known as Caripito itch—the name derived from a river port in Venezuela where this moth caused a memorable epidemic of moth-induced dermatitis.^7,15 Caripito itch is known for intense pruritus that most commonly lasts days or weeks, possibly longer than 1 year.

Diagnostic Difficulties

The challenge of diagnosing a caterpillar- or moth-induced reaction in humans arises from (1) the lack of clinical history (the caterpillar might not be seen at all by the patient or the examiner) and (2) the similarity of these reactions to those with more common triggers.

When setae remain embedded in the skin or mucous membranes, skin scrapings allow accelerated diagnosis. On a skin scraping prepared with 20% potassium hydroxide, setae appear as tapered and barbed hairlike structures, which allows them to be distinguished from other similar-appearing but differently shaped structures, such as glass fibers.

When setae do not remain embedded in the skin or when the cause of the reaction is due to spines, the physician is left with a nonspecific histologic picture and a large differential diagnosis to be narrowed down based on the history and occasionally the pattern of the skin lesion.

A challenge in sting diagnosis is differentiating a caterpillar or moth sting from that of another organism. In certain cases, such as those of the family Megalopygidae, specific patterns of stings might assist in making the diagnosis. Hypersensitivity reactions are associated with a wider differential diagnosis, including irritant or allergic dermatitis from other causes, scabies, eczema, lichen planus, lichen simplex chronicus, seborrheic dermatitis, and tinea corporis, to name a few.⁶ Skin scrapings can be examined for other features, such as burrows in the case of scabies, to further narrow the differential.

Stings and hypersensitivity reactions lacking a proper history and associated with more severe systemic symptoms have caused misdiagnosis or led to a workup for the wrong condition; for example, the picture of abdominal pain, nausea, vomiting, tachycardia, leukocytosis, hypokalemia, and metabolic acidosis can simulate appendicitis.¹⁶ Upon discovery of a puss caterpillar sting in a patient, her symptoms resolved after treatment with ondansetron, morphine, and intravenous fluids.¹⁶

In lonomism, the diagnosis must be established by laboratory measurement of the fibrinogen level, clotting factors, prothrombin time, and activated partial thromboplastin time.⁴ The differential diagnosis associated with lonomism includes disseminated intravascular coagulation (DIC), snakebite, and a hereditary bleeding disorder.⁴ The combination of laboratory tests and an extensive medical history allows a diagnosis. Absence of a personal or family history of bleeding excludes a diagnosis of hereditary bleeding disorder, whereas the absence of known causes of DIC or thrombocytopenia allows DIC to be excluded from the differential.

Treatment Options and Prevention

Treatment—The first step is to remove any embedded setae from the skin or mucous membranes. The stepwise recommendation is to remove any constricted clothing, detach setae with adhesive tape, wash with soap and water, and dry without touching the skin.¹ Any remaining setae can be removed with additional tape or forceps; setae tend to be fragile and are difficult to remove in their entirety.

Other than removal of the setae, skin reactions are treated symptomatically. Ice packs and isopropyl alcohol have been utilized to cool burning or stinging areas. Pain, pruritus, and inflammation have been alleviated with antihistamines and topical corticosteroids.¹ When pain is severe, oral codeine or local injection of anesthetic can be used. For severe and persistent skin lesions, a course of an oral glucocorticoid can be administered. Intramuscular triamcinolone acetonide has been shown to treat pain, dermatitis, and subcutaneous nodules otherwise refractory to treatment.⁸

Antivenin specific for L obliqua exists to treat lonomism and is therefore effective only when lonomism is caused by that species. Lonomism caused by L achelous is treated with cryoprecipitate, purified fibrinogen, and antifibrinolytic drugs, such as aprotinin.⁶ Whole blood and fresh-frozen plasma have been noted to make hemorrhage worse when utilized to treat lonomism. Because the mechanism of action of the venom of Lonomia species is based, in part, on inducing a proinflammatory profile in endothelial cells, studies have demonstrated that inhibition of kallikrein might prevent vascular injury and thus prevent serious adverse effects, such as renal failure.¹⁷

Prevention—People should wear proper protective clothing when outdoors in potentially infested areas. Measures should be taken to ensure that linens and clothing are not left outside in areas where setae might be carried on the wind. Infestation control is necessary if the population of caterpillars reaches a high enough level.

Conclusion

Several species of caterpillars and moths cause adverse reactions in humans: stings, hypersensitivity reactions, and lonomism. Although most reactions are self-limited, some might have more serious effects, including organ failure and death. Mechanisms of injury vary by species of caterpillar, moth, and butterfly; current research is focused on further defining venom components and signaling pathways to isolate potential targets to aid in the diagnosis and treatment of lepidopterism.

To the Editor:

A 56-year-old man with a history of opioid abuse and splenectomy decades prior due to a motor vehicle accident was brought to an outside emergency department with confusion, slurred speech, and difficulty breathing. Over the next few days, he became febrile and hypotensive, requiring vasopressors. Clinical laboratory testing revealed a urine drug screen positive for opioids and a low platelet count in the setting of a rapidly evolving retiform purpuric rash.

The patient was transferred to our institution 6 days after initial presentation with primary diagnoses of septic shock with multiorgan failure and disseminated intravascular coagulation (DIC). Blood cultures were positive for gram-negative rods. After several days of broad-spectrum antibiotics and supportive care, cultures were reported as positive for Capnocytophaga canimorsus. Upon further questioning, the patient’s wife reported that the couple had a new puppy and that the patient often allowed the dog to bite him playfully and lick abrasions on his hands and legs. He had not received medical treatment for any of the dog’s bites.

On initial examination at the time of transfer, the patient’s skin was remarkable for diffuse areas of stellate and retiform purpura with dusky centers and necrosis of the nasal tip and earlobes. Both hands were purpuric, with necrosis of the fingertips (Figure 1A). The flank was marked by large areas of full-thickness sloughing of the skin (Figure 1B). The lower extremities were edematous, with some areas of stellate purpura and numerous large bullae that drained straw-colored fluid (Figure 1C). Lower extremity pulses were found with Doppler ultrasonography.

Given the presence of rapidly developing retiform purpura in the clinical context of severe sepsis, purpura fulminans (PF) was the primary consideration in the differential diagnosis. Levamisole-induced necrosis syndrome also was considered because of necrosis of the ears and nose as well as the history of substance use; however, the patient was not known to have a history of cocaine abuse, and a test of antineutrophil cytoplasmic antibody was negative.

A punch biopsy of the abdomen revealed intravascular thrombi with epidermal and sweat gland necrosis, consistent with PF (Figure 2). Gram, Giemsa, and Gomori methenamine-silver stains were negative for organisms. Tissue culture remained negative. Repeat blood cultures demonstrated Candida parapsilosis fungemia. Respiratory culture was positive for budding yeast.

The patient was treated with antimicrobials, intravenous argatroban, and subcutaneous heparin. Purpura and bullae on the trunk slowly resolved with systemic therapy and wound care with petrolatum and nonadherent dressings. However, lesions on the nasal tip, all fingers of both hands, and several toes evolved into dry gangrene. The hospital course was complicated by renal failure requiring continuous renal replacement therapy; respiratory failure requiring ventilator support; and elevated levels of liver enzymes, consistent with involvement of the hepatic microvasculature.

The patient was in the medical intensive care unit at our institution for 2 weeks and was transferred to a burn center for specialized wound care. At transfer, he was still on a ventilator and receiving continuous renal replacement therapy. Subsequently, the patient required a left above-the-knee amputation, right below-the-knee amputation, and amputation of several digits of the upper extremities. In the months after the amputations, he required multiple stump revisions and experienced surgical site infections that complicated healing.

Purpura fulminans is an uncommon syndrome characterized by intravascular thrombosis and hemorrhagic infarction of the skin. The condition commonly is associated with septic shock, causing vascular collapse and DIC. It often develops rapidly.

Because of associated high mortality, it is important to differentiate PF from other causes of cutaneous retiform purpura, including other causes of thrombosis and large vessel vasculitis. Leading causes of PF include infection and hereditary or acquired deficiency of protein C, protein S, or antithrombin III. Regardless of cause, biopsy results demonstrate vascular thrombosis out of proportion to vasculitis. The mortality rate is 42% to 50%. The incidence of postinfectious sepsis sequelae in PF is higher than in survivors of sepsis only, especially amputation.^1-3 Most patients do not die from complications of sepsis but from sequelae of the hypercoagulable and prothrombotic state associated with PF.⁴ Hemorrhagic infarction can affect the kidneys, brain, lungs, heart, eyes, and adrenal glands (ie, necrosis, namely Waterhouse-Friderichsen syndrome).⁵

The most common infectious cause of PF is sepsis secondary to Neisseria meningitidis, with as many as 25% of infected patients developing PF.⁶Streptococcus pneumoniae is another common cause. Other important causative organisms include Streptococcus pyogenes; Staphylococcus aureus (in the setting of intravenous substance use); Klebsiella oxytoca; Klebsiella aerogenes; rickettsial organisms; and viruses, including cytomegalovirus and varicella-zoster virus.^2,7-13 Two earlier cases associated with Capnocytophaga were characterized by concomitant renal failure, metabolic acidosis, hemolytic anemia, and DIC.¹⁴

It is estimated that Capnocytophaga causes 11% to 46% of all cases of sepsis¹⁵; sepsis resulting from Capnocytophaga has extremely poor outcomes, with mortality reaching as high as 60%. The organism is part of the normal oral flora of cats and dogs, and a bite (less often, a scratch) is the cause of most Capnocytophaga infections. The clinical spectrum of C canimorsus infection associated with dog saliva exposure more commonly includes cellulitis at or around the site of inoculation, meningitis, and endocarditis.¹⁶

Although patients affected by PF can be young and healthy, several risk factors for PF have been identified^2,6,16: asplenia, an immunocompromised state, systemic corticosteroid use, cirrhosis, and alcoholism. Asplenic patients have been shown to be particularly susceptible to systemic Capnocytophaga infection; when bitten by a dog, they should be treated with prophylactic antibiotics to cover Capnocytophaga.¹⁷ Immunocompetent patients rarely develop severe infection with Capnocytophaga.^16,18,19 The complement system in particular is critically important in defending against C canimorsus.²⁰

The underlying pathophysiology of acute infectious PF is multifactorial, encompassing increased expression of procoagulant tissue factor by monocytes and endothelial cells in the presence of bacterial pathogens. Dysfunction of protein C, an anticoagulant component of the coagulation cascade, often is cited as a crucial derangement leading to the development of a prothrombotic state in acute infectious PF.²¹ Serum protein S and antithrombin deficiency also can play a role.²² Specific in vitro examination of C canimorsus has revealed a protease that catalyzes N-terminal cleavage of procoagulant factor X, resulting in loss of function.¹⁵

Retiform purpura is a hallmark feature of PF, often beginning as nonblanching erythema with localized edema and petechiae before evolving into the characteristic stellate lesions with hemorrhagic bullae and subsequent necrosis.²³ Pathologic examination reveals microthrombi involving arterioles and smaller vessels.²⁴ There typically is laboratory evidence of DIC in PF, including elevated prothrombin time and partial thromboplastin time, thrombocytopenia, elevated D-dimer, and a decreased fibrinogen level.^6,23

Capnocytophaga bacteria are challenging to grow on standard culture media. Optimal media for growth include 5% sheep’s blood and chocolate agar.¹⁶ Polymerase chain reaction can identify Capnocytophaga; in cases in which blood culture does not produce growth, 16S ribosomal RNA gene sequencing of tissue from skin biopsy has identified the pathogen.²⁵

Some Capnocytophaga isolates have been shown to produce beta-lactamase; individual strains can be resistant to penicillins, cephalosporins, and imipenem.²⁶ Factors associated with an increased risk for death include decreased leukocyte and platelet counts and an increased level of arterial lactate.²⁷

Empiric antibiotic therapy for Capnocytophaga sepsis should include a beta-lactam and beta-lactamase inhibitor, such as piperacillin-tazobactam. Management of DIC can include therapeutic heparin or low-molecular-weight heparin and prophylactic platelet transfusion to maintain a pre-established value.^28-30 Debridement should be conservative; it is important to wait for definite delineation between viable and necrotic tissue,³¹ which might take several months.³² Human skin allografts, in addition to artificial skin, are utilized as supplemental therapy for more rapid wound closure after removal of necrotic tissue.^33,34 Hyperoxygenated fatty acids have been noted to aid in more rapid wound healing in infants with PF.³⁵

Fresh frozen plasma is one method to replace missing factors, but it contains little protein C.³⁶ Outcomes with recombinant human activated protein C (drotrecogin alfa) are mixed, and studies have shown no benefit in reducing the risk for death.^37,38 Protein C concentrate has shown therapeutic benefit in some case reports and small retrospective studies.⁴ In one case report, protein C concentrate and heparin were utilized in combination with antithrombin III.²¹

Hyperbaric O₂ might be of benefit when initiated within 5 days after onset of PF. However, hyperbaric O₂ does carry risk; O₂ toxicity, barotrauma, and barriers to timely resuscitation when the patient is inside the pressurized chamber can occur.²

There is a single report of successful use of the vasodilator iloprost for meningococcal PF without need for surgical intervention; the team also utilized topical nitroglycerin patches on the fingers to avoid digital amputation.³⁹ Epoprostenol, tissue plasminogen activator, and antithrombin have been utilized in cases of extensive PF. Fibrinolytic therapy might have some utility, but only in a setting of malignancy-associated DIC.⁴⁰

Treatment of acute infectious PF lacks a high level of evidence. Options include replacement of anticoagulant factors, anticoagulant therapy, hyperbaric O₂, topical and systemic vasodilators, and, in the setting of underlying cancer, fibrinolytics. Even with therapy, prognosis is guarded.

To the Editor:

A 56-year-old man with a history of opioid abuse and splenectomy decades prior due to a motor vehicle accident was brought to an outside emergency department with confusion, slurred speech, and difficulty breathing. Over the next few days, he became febrile and hypotensive, requiring vasopressors. Clinical laboratory testing revealed a urine drug screen positive for opioids and a low platelet count in the setting of a rapidly evolving retiform purpuric rash.

The patient was transferred to our institution 6 days after initial presentation with primary diagnoses of septic shock with multiorgan failure and disseminated intravascular coagulation (DIC). Blood cultures were positive for gram-negative rods. After several days of broad-spectrum antibiotics and supportive care, cultures were reported as positive for Capnocytophaga canimorsus. Upon further questioning, the patient’s wife reported that the couple had a new puppy and that the patient often allowed the dog to bite him playfully and lick abrasions on his hands and legs. He had not received medical treatment for any of the dog’s bites.

On initial examination at the time of transfer, the patient’s skin was remarkable for diffuse areas of stellate and retiform purpura with dusky centers and necrosis of the nasal tip and earlobes. Both hands were purpuric, with necrosis of the fingertips (Figure 1A). The flank was marked by large areas of full-thickness sloughing of the skin (Figure 1B). The lower extremities were edematous, with some areas of stellate purpura and numerous large bullae that drained straw-colored fluid (Figure 1C). Lower extremity pulses were found with Doppler ultrasonography.

Given the presence of rapidly developing retiform purpura in the clinical context of severe sepsis, purpura fulminans (PF) was the primary consideration in the differential diagnosis. Levamisole-induced necrosis syndrome also was considered because of necrosis of the ears and nose as well as the history of substance use; however, the patient was not known to have a history of cocaine abuse, and a test of antineutrophil cytoplasmic antibody was negative.

A punch biopsy of the abdomen revealed intravascular thrombi with epidermal and sweat gland necrosis, consistent with PF (Figure 2). Gram, Giemsa, and Gomori methenamine-silver stains were negative for organisms. Tissue culture remained negative. Repeat blood cultures demonstrated Candida parapsilosis fungemia. Respiratory culture was positive for budding yeast.

The patient was treated with antimicrobials, intravenous argatroban, and subcutaneous heparin. Purpura and bullae on the trunk slowly resolved with systemic therapy and wound care with petrolatum and nonadherent dressings. However, lesions on the nasal tip, all fingers of both hands, and several toes evolved into dry gangrene. The hospital course was complicated by renal failure requiring continuous renal replacement therapy; respiratory failure requiring ventilator support; and elevated levels of liver enzymes, consistent with involvement of the hepatic microvasculature.

The patient was in the medical intensive care unit at our institution for 2 weeks and was transferred to a burn center for specialized wound care. At transfer, he was still on a ventilator and receiving continuous renal replacement therapy. Subsequently, the patient required a left above-the-knee amputation, right below-the-knee amputation, and amputation of several digits of the upper extremities. In the months after the amputations, he required multiple stump revisions and experienced surgical site infections that complicated healing.

Purpura fulminans is an uncommon syndrome characterized by intravascular thrombosis and hemorrhagic infarction of the skin. The condition commonly is associated with septic shock, causing vascular collapse and DIC. It often develops rapidly.

Because of associated high mortality, it is important to differentiate PF from other causes of cutaneous retiform purpura, including other causes of thrombosis and large vessel vasculitis. Leading causes of PF include infection and hereditary or acquired deficiency of protein C, protein S, or antithrombin III. Regardless of cause, biopsy results demonstrate vascular thrombosis out of proportion to vasculitis. The mortality rate is 42% to 50%. The incidence of postinfectious sepsis sequelae in PF is higher than in survivors of sepsis only, especially amputation.^1-3 Most patients do not die from complications of sepsis but from sequelae of the hypercoagulable and prothrombotic state associated with PF.⁴ Hemorrhagic infarction can affect the kidneys, brain, lungs, heart, eyes, and adrenal glands (ie, necrosis, namely Waterhouse-Friderichsen syndrome).⁵

The most common infectious cause of PF is sepsis secondary to Neisseria meningitidis, with as many as 25% of infected patients developing PF.⁶Streptococcus pneumoniae is another common cause. Other important causative organisms include Streptococcus pyogenes; Staphylococcus aureus (in the setting of intravenous substance use); Klebsiella oxytoca; Klebsiella aerogenes; rickettsial organisms; and viruses, including cytomegalovirus and varicella-zoster virus.^2,7-13 Two earlier cases associated with Capnocytophaga were characterized by concomitant renal failure, metabolic acidosis, hemolytic anemia, and DIC.¹⁴

It is estimated that Capnocytophaga causes 11% to 46% of all cases of sepsis¹⁵; sepsis resulting from Capnocytophaga has extremely poor outcomes, with mortality reaching as high as 60%. The organism is part of the normal oral flora of cats and dogs, and a bite (less often, a scratch) is the cause of most Capnocytophaga infections. The clinical spectrum of C canimorsus infection associated with dog saliva exposure more commonly includes cellulitis at or around the site of inoculation, meningitis, and endocarditis.¹⁶

Although patients affected by PF can be young and healthy, several risk factors for PF have been identified^2,6,16: asplenia, an immunocompromised state, systemic corticosteroid use, cirrhosis, and alcoholism. Asplenic patients have been shown to be particularly susceptible to systemic Capnocytophaga infection; when bitten by a dog, they should be treated with prophylactic antibiotics to cover Capnocytophaga.¹⁷ Immunocompetent patients rarely develop severe infection with Capnocytophaga.^16,18,19 The complement system in particular is critically important in defending against C canimorsus.²⁰

The underlying pathophysiology of acute infectious PF is multifactorial, encompassing increased expression of procoagulant tissue factor by monocytes and endothelial cells in the presence of bacterial pathogens. Dysfunction of protein C, an anticoagulant component of the coagulation cascade, often is cited as a crucial derangement leading to the development of a prothrombotic state in acute infectious PF.²¹ Serum protein S and antithrombin deficiency also can play a role.²² Specific in vitro examination of C canimorsus has revealed a protease that catalyzes N-terminal cleavage of procoagulant factor X, resulting in loss of function.¹⁵

Retiform purpura is a hallmark feature of PF, often beginning as nonblanching erythema with localized edema and petechiae before evolving into the characteristic stellate lesions with hemorrhagic bullae and subsequent necrosis.²³ Pathologic examination reveals microthrombi involving arterioles and smaller vessels.²⁴ There typically is laboratory evidence of DIC in PF, including elevated prothrombin time and partial thromboplastin time, thrombocytopenia, elevated D-dimer, and a decreased fibrinogen level.^6,23

Capnocytophaga bacteria are challenging to grow on standard culture media. Optimal media for growth include 5% sheep’s blood and chocolate agar.¹⁶ Polymerase chain reaction can identify Capnocytophaga; in cases in which blood culture does not produce growth, 16S ribosomal RNA gene sequencing of tissue from skin biopsy has identified the pathogen.²⁵

Some Capnocytophaga isolates have been shown to produce beta-lactamase; individual strains can be resistant to penicillins, cephalosporins, and imipenem.²⁶ Factors associated with an increased risk for death include decreased leukocyte and platelet counts and an increased level of arterial lactate.²⁷

Empiric antibiotic therapy for Capnocytophaga sepsis should include a beta-lactam and beta-lactamase inhibitor, such as piperacillin-tazobactam. Management of DIC can include therapeutic heparin or low-molecular-weight heparin and prophylactic platelet transfusion to maintain a pre-established value.^28-30 Debridement should be conservative; it is important to wait for definite delineation between viable and necrotic tissue,³¹ which might take several months.³² Human skin allografts, in addition to artificial skin, are utilized as supplemental therapy for more rapid wound closure after removal of necrotic tissue.^33,34 Hyperoxygenated fatty acids have been noted to aid in more rapid wound healing in infants with PF.³⁵

Fresh frozen plasma is one method to replace missing factors, but it contains little protein C.³⁶ Outcomes with recombinant human activated protein C (drotrecogin alfa) are mixed, and studies have shown no benefit in reducing the risk for death.^37,38 Protein C concentrate has shown therapeutic benefit in some case reports and small retrospective studies.⁴ In one case report, protein C concentrate and heparin were utilized in combination with antithrombin III.²¹

Hyperbaric O₂ might be of benefit when initiated within 5 days after onset of PF. However, hyperbaric O₂ does carry risk; O₂ toxicity, barotrauma, and barriers to timely resuscitation when the patient is inside the pressurized chamber can occur.²

There is a single report of successful use of the vasodilator iloprost for meningococcal PF without need for surgical intervention; the team also utilized topical nitroglycerin patches on the fingers to avoid digital amputation.³⁹ Epoprostenol, tissue plasminogen activator, and antithrombin have been utilized in cases of extensive PF. Fibrinolytic therapy might have some utility, but only in a setting of malignancy-associated DIC.⁴⁰

Treatment of acute infectious PF lacks a high level of evidence. Options include replacement of anticoagulant factors, anticoagulant therapy, hyperbaric O₂, topical and systemic vasodilators, and, in the setting of underlying cancer, fibrinolytics. Even with therapy, prognosis is guarded.

To the Editor:

A 56-year-old man with a history of opioid abuse and splenectomy decades prior due to a motor vehicle accident was brought to an outside emergency department with confusion, slurred speech, and difficulty breathing. Over the next few days, he became febrile and hypotensive, requiring vasopressors. Clinical laboratory testing revealed a urine drug screen positive for opioids and a low platelet count in the setting of a rapidly evolving retiform purpuric rash.

The patient was transferred to our institution 6 days after initial presentation with primary diagnoses of septic shock with multiorgan failure and disseminated intravascular coagulation (DIC). Blood cultures were positive for gram-negative rods. After several days of broad-spectrum antibiotics and supportive care, cultures were reported as positive for Capnocytophaga canimorsus. Upon further questioning, the patient’s wife reported that the couple had a new puppy and that the patient often allowed the dog to bite him playfully and lick abrasions on his hands and legs. He had not received medical treatment for any of the dog’s bites.

On initial examination at the time of transfer, the patient’s skin was remarkable for diffuse areas of stellate and retiform purpura with dusky centers and necrosis of the nasal tip and earlobes. Both hands were purpuric, with necrosis of the fingertips (Figure 1A). The flank was marked by large areas of full-thickness sloughing of the skin (Figure 1B). The lower extremities were edematous, with some areas of stellate purpura and numerous large bullae that drained straw-colored fluid (Figure 1C). Lower extremity pulses were found with Doppler ultrasonography.

Given the presence of rapidly developing retiform purpura in the clinical context of severe sepsis, purpura fulminans (PF) was the primary consideration in the differential diagnosis. Levamisole-induced necrosis syndrome also was considered because of necrosis of the ears and nose as well as the history of substance use; however, the patient was not known to have a history of cocaine abuse, and a test of antineutrophil cytoplasmic antibody was negative.

A punch biopsy of the abdomen revealed intravascular thrombi with epidermal and sweat gland necrosis, consistent with PF (Figure 2). Gram, Giemsa, and Gomori methenamine-silver stains were negative for organisms. Tissue culture remained negative. Repeat blood cultures demonstrated Candida parapsilosis fungemia. Respiratory culture was positive for budding yeast.

The patient was treated with antimicrobials, intravenous argatroban, and subcutaneous heparin. Purpura and bullae on the trunk slowly resolved with systemic therapy and wound care with petrolatum and nonadherent dressings. However, lesions on the nasal tip, all fingers of both hands, and several toes evolved into dry gangrene. The hospital course was complicated by renal failure requiring continuous renal replacement therapy; respiratory failure requiring ventilator support; and elevated levels of liver enzymes, consistent with involvement of the hepatic microvasculature.

The patient was in the medical intensive care unit at our institution for 2 weeks and was transferred to a burn center for specialized wound care. At transfer, he was still on a ventilator and receiving continuous renal replacement therapy. Subsequently, the patient required a left above-the-knee amputation, right below-the-knee amputation, and amputation of several digits of the upper extremities. In the months after the amputations, he required multiple stump revisions and experienced surgical site infections that complicated healing.

Purpura fulminans is an uncommon syndrome characterized by intravascular thrombosis and hemorrhagic infarction of the skin. The condition commonly is associated with septic shock, causing vascular collapse and DIC. It often develops rapidly.

Because of associated high mortality, it is important to differentiate PF from other causes of cutaneous retiform purpura, including other causes of thrombosis and large vessel vasculitis. Leading causes of PF include infection and hereditary or acquired deficiency of protein C, protein S, or antithrombin III. Regardless of cause, biopsy results demonstrate vascular thrombosis out of proportion to vasculitis. The mortality rate is 42% to 50%. The incidence of postinfectious sepsis sequelae in PF is higher than in survivors of sepsis only, especially amputation.^1-3 Most patients do not die from complications of sepsis but from sequelae of the hypercoagulable and prothrombotic state associated with PF.⁴ Hemorrhagic infarction can affect the kidneys, brain, lungs, heart, eyes, and adrenal glands (ie, necrosis, namely Waterhouse-Friderichsen syndrome).⁵

The most common infectious cause of PF is sepsis secondary to Neisseria meningitidis, with as many as 25% of infected patients developing PF.⁶Streptococcus pneumoniae is another common cause. Other important causative organisms include Streptococcus pyogenes; Staphylococcus aureus (in the setting of intravenous substance use); Klebsiella oxytoca; Klebsiella aerogenes; rickettsial organisms; and viruses, including cytomegalovirus and varicella-zoster virus.^2,7-13 Two earlier cases associated with Capnocytophaga were characterized by concomitant renal failure, metabolic acidosis, hemolytic anemia, and DIC.¹⁴

It is estimated that Capnocytophaga causes 11% to 46% of all cases of sepsis¹⁵; sepsis resulting from Capnocytophaga has extremely poor outcomes, with mortality reaching as high as 60%. The organism is part of the normal oral flora of cats and dogs, and a bite (less often, a scratch) is the cause of most Capnocytophaga infections. The clinical spectrum of C canimorsus infection associated with dog saliva exposure more commonly includes cellulitis at or around the site of inoculation, meningitis, and endocarditis.¹⁶

Although patients affected by PF can be young and healthy, several risk factors for PF have been identified^2,6,16: asplenia, an immunocompromised state, systemic corticosteroid use, cirrhosis, and alcoholism. Asplenic patients have been shown to be particularly susceptible to systemic Capnocytophaga infection; when bitten by a dog, they should be treated with prophylactic antibiotics to cover Capnocytophaga.¹⁷ Immunocompetent patients rarely develop severe infection with Capnocytophaga.^16,18,19 The complement system in particular is critically important in defending against C canimorsus.²⁰

The underlying pathophysiology of acute infectious PF is multifactorial, encompassing increased expression of procoagulant tissue factor by monocytes and endothelial cells in the presence of bacterial pathogens. Dysfunction of protein C, an anticoagulant component of the coagulation cascade, often is cited as a crucial derangement leading to the development of a prothrombotic state in acute infectious PF.²¹ Serum protein S and antithrombin deficiency also can play a role.²² Specific in vitro examination of C canimorsus has revealed a protease that catalyzes N-terminal cleavage of procoagulant factor X, resulting in loss of function.¹⁵

Retiform purpura is a hallmark feature of PF, often beginning as nonblanching erythema with localized edema and petechiae before evolving into the characteristic stellate lesions with hemorrhagic bullae and subsequent necrosis.²³ Pathologic examination reveals microthrombi involving arterioles and smaller vessels.²⁴ There typically is laboratory evidence of DIC in PF, including elevated prothrombin time and partial thromboplastin time, thrombocytopenia, elevated D-dimer, and a decreased fibrinogen level.^6,23

Capnocytophaga bacteria are challenging to grow on standard culture media. Optimal media for growth include 5% sheep’s blood and chocolate agar.¹⁶ Polymerase chain reaction can identify Capnocytophaga; in cases in which blood culture does not produce growth, 16S ribosomal RNA gene sequencing of tissue from skin biopsy has identified the pathogen.²⁵

Some Capnocytophaga isolates have been shown to produce beta-lactamase; individual strains can be resistant to penicillins, cephalosporins, and imipenem.²⁶ Factors associated with an increased risk for death include decreased leukocyte and platelet counts and an increased level of arterial lactate.²⁷

Empiric antibiotic therapy for Capnocytophaga sepsis should include a beta-lactam and beta-lactamase inhibitor, such as piperacillin-tazobactam. Management of DIC can include therapeutic heparin or low-molecular-weight heparin and prophylactic platelet transfusion to maintain a pre-established value.^28-30 Debridement should be conservative; it is important to wait for definite delineation between viable and necrotic tissue,³¹ which might take several months.³² Human skin allografts, in addition to artificial skin, are utilized as supplemental therapy for more rapid wound closure after removal of necrotic tissue.^33,34 Hyperoxygenated fatty acids have been noted to aid in more rapid wound healing in infants with PF.³⁵

Fresh frozen plasma is one method to replace missing factors, but it contains little protein C.³⁶ Outcomes with recombinant human activated protein C (drotrecogin alfa) are mixed, and studies have shown no benefit in reducing the risk for death.^37,38 Protein C concentrate has shown therapeutic benefit in some case reports and small retrospective studies.⁴ In one case report, protein C concentrate and heparin were utilized in combination with antithrombin III.²¹

Hyperbaric O₂ might be of benefit when initiated within 5 days after onset of PF. However, hyperbaric O₂ does carry risk; O₂ toxicity, barotrauma, and barriers to timely resuscitation when the patient is inside the pressurized chamber can occur.²

There is a single report of successful use of the vasodilator iloprost for meningococcal PF without need for surgical intervention; the team also utilized topical nitroglycerin patches on the fingers to avoid digital amputation.³⁹ Epoprostenol, tissue plasminogen activator, and antithrombin have been utilized in cases of extensive PF. Fibrinolytic therapy might have some utility, but only in a setting of malignancy-associated DIC.⁴⁰

Treatment of acute infectious PF lacks a high level of evidence. Options include replacement of anticoagulant factors, anticoagulant therapy, hyperbaric O₂, topical and systemic vasodilators, and, in the setting of underlying cancer, fibrinolytics. Even with therapy, prognosis is guarded.

Bloodroot (Sanguinaria canadensis) is a member of the family Papaveraceae.¹ This North American plant commonly is found in widespread distribution from Nova Scotia, Canada, to Florida and from the Great Lakes to Mississippi.² Historically, Native Americans used bloodroot as a skin dye and as a medicine for many ailments.³

Bloodroot blooms for only a few days, starting in March, and fruits in June. The flowers comprise 8 to 10 white petals, surrounding a bed of yellow stamens (Figure). The plant thrives in wooded areas and grows to 12 inches tall. In its off-season, the plant remains dormant and can survive below-freezing temperatures.⁴

Chemical Constituents

Bloodroot gets its colloquial name from its red sap, which is released when the plant’s rhizome is cut. This sap contains a high concentration of alkaloids that are used for protection against predators. The rhizome itself has a rusty, red-brown color; the roots are a brighter red-orange.⁴

The rhizome of S canadensis contains the highest concentration of active alkaloids; the roots also contain these chemicals, though to a lesser degree; and the leaves, flowers, and fruits harvest approximately 1% of the alkaloids found in the roots.⁴ The concentration of alkaloids can vary from one plant to the next, depending on environmental conditions.^5,6

The major alkaloids in S canadensis include both quaternary benzophenanthridine alkaloids (eg, sanguinarine, chelerythrine, sanguilutine, chelilutine, sanguirubine, chelirubine) and protopin alkaloids (eg, protopine, allocryptopine).^3,7 Of these, sanguinarine and chelerythrine typically are the most potent.¹ Oral ingestion or topical application of these molecules can have therapeutic and toxic effects.⁸

Biophysiological Effects

Bloodroot has been shown to have remarkable antimicrobial effects.⁹ The plant produces hydrogen peroxide and superoxide anion.¹⁰ These mediators cause oxidative stress, thus inducing destruction of cellular DNA and the cell membrane.¹¹ Although these effects can be helpful when fighting infection, they are not necessarily selective against healthy cells.¹²

Alkaloids of bloodroot also have cardiovascular therapeutic effects. Sanguinarine blocks angiotensin II and causes vasodilation, thus helping treat hypertension.¹³ It also acts as an inotrope by blocking the Na⁺/K⁺ ATPase pump. These effects in a patient who is already taking digoxin can cause notable cardiotoxicity because the 2 drugs share a mechanism of action.¹⁴

Chelerythrine blocks production of cyclooxygenase 2 and prostaglandin E₂.¹⁵ This pathway modification results in anti-inflammatory effects that can help treat arthritis, edema, and other inflammatory conditions.¹⁶ Moreover, sanguinarine has demonstrated efficacy in numerous anticancer pathways,¹⁷ including downregulation of intercellular adhesion molecules, vascular cell adhesion molecules, and vascular endothelial growth factor (VEGF).^18-20 Blocking VEGF is one way to inhibit angiogenesis,²¹ which is upregulated in tumor formation, thus sanguinarine can have an antiproliferative anticancer effect.²² Sanguinarine also upregulates molecules such as nuclear factor–κB and the protease enzymes known as caspases to cause proapoptotic effects, furthering its antitumor potential.^23,24

Treatment of Dermatologic Conditions

The initial technique of Mohs micrographic surgery employed a chemopaste that utilized an extract of S canadensis to preserve tissue.²⁵ Outside the dermatologist’s office, bloodroot is used as a topical home remedy for a variety of cutaneous conditions, including cancer, skin tags, and warts.²⁶ Bloodroot is advertised as black salve, an alternative anticancer treatment.^27,28

As useful as this natural agent sounds, it has a pitfall: The alkaloids of S canadensis are nonspecific in their cytotoxicity, damaging neoplastic and healthy tissue.²⁹ This cytotoxic effect can cause escharification through diffuse tissue destruction and has been observed to result in formation of a keloid scar.³⁰ The alkaloids in black salve also have been shown to cause skin erosions and cellular atypia.^28,31 Therefore, the utility of this escharotic in medical treatment is limited.³² Fortuitously, oral antibiotics and wound care can help address this adverse effect.²⁸

Bloodroot was once used as a mouth rinse and toothpaste to treat gingivitis, but this application was later associated with oral leukoplakia, a premalignant condition.³³ Leukoplakia associated with S canadensis extract often is unremitting. Immediate discontinuation of the offending agent produces little regression, suggesting that cellular damage is irreversible.³⁴

Final Thoughts

Although bloodroot demonstrates efficacy as a phytotherapeutic, it does come with notable toxicity. Physicians should warn patients of the unwanted cosmetic effects of black salve, especially oral products that incorporate sanguinarine. Adverse effects on the oropharynx can be irreversible, though the eschar associated with black salve can be treated with a topical or oral corticosteroid.²⁹

Bloodroot (Sanguinaria canadensis) is a member of the family Papaveraceae.¹ This North American plant commonly is found in widespread distribution from Nova Scotia, Canada, to Florida and from the Great Lakes to Mississippi.² Historically, Native Americans used bloodroot as a skin dye and as a medicine for many ailments.³

Bloodroot blooms for only a few days, starting in March, and fruits in June. The flowers comprise 8 to 10 white petals, surrounding a bed of yellow stamens (Figure). The plant thrives in wooded areas and grows to 12 inches tall. In its off-season, the plant remains dormant and can survive below-freezing temperatures.⁴

Chemical Constituents

Bloodroot gets its colloquial name from its red sap, which is released when the plant’s rhizome is cut. This sap contains a high concentration of alkaloids that are used for protection against predators. The rhizome itself has a rusty, red-brown color; the roots are a brighter red-orange.⁴

The rhizome of S canadensis contains the highest concentration of active alkaloids; the roots also contain these chemicals, though to a lesser degree; and the leaves, flowers, and fruits harvest approximately 1% of the alkaloids found in the roots.⁴ The concentration of alkaloids can vary from one plant to the next, depending on environmental conditions.^5,6

The major alkaloids in S canadensis include both quaternary benzophenanthridine alkaloids (eg, sanguinarine, chelerythrine, sanguilutine, chelilutine, sanguirubine, chelirubine) and protopin alkaloids (eg, protopine, allocryptopine).^3,7 Of these, sanguinarine and chelerythrine typically are the most potent.¹ Oral ingestion or topical application of these molecules can have therapeutic and toxic effects.⁸

Biophysiological Effects

Bloodroot has been shown to have remarkable antimicrobial effects.⁹ The plant produces hydrogen peroxide and superoxide anion.¹⁰ These mediators cause oxidative stress, thus inducing destruction of cellular DNA and the cell membrane.¹¹ Although these effects can be helpful when fighting infection, they are not necessarily selective against healthy cells.¹²

Alkaloids of bloodroot also have cardiovascular therapeutic effects. Sanguinarine blocks angiotensin II and causes vasodilation, thus helping treat hypertension.¹³ It also acts as an inotrope by blocking the Na⁺/K⁺ ATPase pump. These effects in a patient who is already taking digoxin can cause notable cardiotoxicity because the 2 drugs share a mechanism of action.¹⁴

Chelerythrine blocks production of cyclooxygenase 2 and prostaglandin E₂.¹⁵ This pathway modification results in anti-inflammatory effects that can help treat arthritis, edema, and other inflammatory conditions.¹⁶ Moreover, sanguinarine has demonstrated efficacy in numerous anticancer pathways,¹⁷ including downregulation of intercellular adhesion molecules, vascular cell adhesion molecules, and vascular endothelial growth factor (VEGF).^18-20 Blocking VEGF is one way to inhibit angiogenesis,²¹ which is upregulated in tumor formation, thus sanguinarine can have an antiproliferative anticancer effect.²² Sanguinarine also upregulates molecules such as nuclear factor–κB and the protease enzymes known as caspases to cause proapoptotic effects, furthering its antitumor potential.^23,24

Treatment of Dermatologic Conditions

The initial technique of Mohs micrographic surgery employed a chemopaste that utilized an extract of S canadensis to preserve tissue.²⁵ Outside the dermatologist’s office, bloodroot is used as a topical home remedy for a variety of cutaneous conditions, including cancer, skin tags, and warts.²⁶ Bloodroot is advertised as black salve, an alternative anticancer treatment.^27,28

As useful as this natural agent sounds, it has a pitfall: The alkaloids of S canadensis are nonspecific in their cytotoxicity, damaging neoplastic and healthy tissue.²⁹ This cytotoxic effect can cause escharification through diffuse tissue destruction and has been observed to result in formation of a keloid scar.³⁰ The alkaloids in black salve also have been shown to cause skin erosions and cellular atypia.^28,31 Therefore, the utility of this escharotic in medical treatment is limited.³² Fortuitously, oral antibiotics and wound care can help address this adverse effect.²⁸

Bloodroot was once used as a mouth rinse and toothpaste to treat gingivitis, but this application was later associated with oral leukoplakia, a premalignant condition.³³ Leukoplakia associated with S canadensis extract often is unremitting. Immediate discontinuation of the offending agent produces little regression, suggesting that cellular damage is irreversible.³⁴

Final Thoughts

Although bloodroot demonstrates efficacy as a phytotherapeutic, it does come with notable toxicity. Physicians should warn patients of the unwanted cosmetic effects of black salve, especially oral products that incorporate sanguinarine. Adverse effects on the oropharynx can be irreversible, though the eschar associated with black salve can be treated with a topical or oral corticosteroid.²⁹

Bloodroot (Sanguinaria canadensis) is a member of the family Papaveraceae.¹ This North American plant commonly is found in widespread distribution from Nova Scotia, Canada, to Florida and from the Great Lakes to Mississippi.² Historically, Native Americans used bloodroot as a skin dye and as a medicine for many ailments.³

Bloodroot blooms for only a few days, starting in March, and fruits in June. The flowers comprise 8 to 10 white petals, surrounding a bed of yellow stamens (Figure). The plant thrives in wooded areas and grows to 12 inches tall. In its off-season, the plant remains dormant and can survive below-freezing temperatures.⁴

Chemical Constituents

Bloodroot gets its colloquial name from its red sap, which is released when the plant’s rhizome is cut. This sap contains a high concentration of alkaloids that are used for protection against predators. The rhizome itself has a rusty, red-brown color; the roots are a brighter red-orange.⁴

The rhizome of S canadensis contains the highest concentration of active alkaloids; the roots also contain these chemicals, though to a lesser degree; and the leaves, flowers, and fruits harvest approximately 1% of the alkaloids found in the roots.⁴ The concentration of alkaloids can vary from one plant to the next, depending on environmental conditions.^5,6

The major alkaloids in S canadensis include both quaternary benzophenanthridine alkaloids (eg, sanguinarine, chelerythrine, sanguilutine, chelilutine, sanguirubine, chelirubine) and protopin alkaloids (eg, protopine, allocryptopine).^3,7 Of these, sanguinarine and chelerythrine typically are the most potent.¹ Oral ingestion or topical application of these molecules can have therapeutic and toxic effects.⁸

Biophysiological Effects

Bloodroot has been shown to have remarkable antimicrobial effects.⁹ The plant produces hydrogen peroxide and superoxide anion.¹⁰ These mediators cause oxidative stress, thus inducing destruction of cellular DNA and the cell membrane.¹¹ Although these effects can be helpful when fighting infection, they are not necessarily selective against healthy cells.¹²

Alkaloids of bloodroot also have cardiovascular therapeutic effects. Sanguinarine blocks angiotensin II and causes vasodilation, thus helping treat hypertension.¹³ It also acts as an inotrope by blocking the Na⁺/K⁺ ATPase pump. These effects in a patient who is already taking digoxin can cause notable cardiotoxicity because the 2 drugs share a mechanism of action.¹⁴

Chelerythrine blocks production of cyclooxygenase 2 and prostaglandin E₂.¹⁵ This pathway modification results in anti-inflammatory effects that can help treat arthritis, edema, and other inflammatory conditions.¹⁶ Moreover, sanguinarine has demonstrated efficacy in numerous anticancer pathways,¹⁷ including downregulation of intercellular adhesion molecules, vascular cell adhesion molecules, and vascular endothelial growth factor (VEGF).^18-20 Blocking VEGF is one way to inhibit angiogenesis,²¹ which is upregulated in tumor formation, thus sanguinarine can have an antiproliferative anticancer effect.²² Sanguinarine also upregulates molecules such as nuclear factor–κB and the protease enzymes known as caspases to cause proapoptotic effects, furthering its antitumor potential.^23,24

Treatment of Dermatologic Conditions

The initial technique of Mohs micrographic surgery employed a chemopaste that utilized an extract of S canadensis to preserve tissue.²⁵ Outside the dermatologist’s office, bloodroot is used as a topical home remedy for a variety of cutaneous conditions, including cancer, skin tags, and warts.²⁶ Bloodroot is advertised as black salve, an alternative anticancer treatment.^27,28

As useful as this natural agent sounds, it has a pitfall: The alkaloids of S canadensis are nonspecific in their cytotoxicity, damaging neoplastic and healthy tissue.²⁹ This cytotoxic effect can cause escharification through diffuse tissue destruction and has been observed to result in formation of a keloid scar.³⁰ The alkaloids in black salve also have been shown to cause skin erosions and cellular atypia.^28,31 Therefore, the utility of this escharotic in medical treatment is limited.³² Fortuitously, oral antibiotics and wound care can help address this adverse effect.²⁸

Bloodroot was once used as a mouth rinse and toothpaste to treat gingivitis, but this application was later associated with oral leukoplakia, a premalignant condition.³³ Leukoplakia associated with S canadensis extract often is unremitting. Immediate discontinuation of the offending agent produces little regression, suggesting that cellular damage is irreversible.³⁴

Final Thoughts

Although bloodroot demonstrates efficacy as a phytotherapeutic, it does come with notable toxicity. Physicians should warn patients of the unwanted cosmetic effects of black salve, especially oral products that incorporate sanguinarine. Adverse effects on the oropharynx can be irreversible, though the eschar associated with black salve can be treated with a topical or oral corticosteroid.²⁹

Sea cucumbers—commonly known as trepang in Indonesia, namako in Japan, and hai shen in China, where they are treasured as a food delicacy—are sea creatures belonging to the phylum Echinodermata, class Holothuridea, and family Cucumariidae . ^1,2 They are an integral part of a variety of marine habitats, serving as cleaners as they filter through sediment for nutrients. They can be found on the ocean floor under hundreds of feet of water or in shallow sandy waters along the coast, but they most commonly are found living among coral reefs. Sea cucumbers look just as they sound—shaped like cucumbers or sausages, ranging from under 1 inch to upwards of 6 feet in length depending on the specific species (Figure 1). They have a group of tentacles around the mouth used for filtering sediment, and they move about the ocean floor on tubular feet protruding through the body wall, similar to a sea star.

Beneficial Properties and Cultural Relevance

Although more than 1200 species of sea cucumbers have been identified thus far, only about 20 of these are edible.² The most common of the edible species is Stichopus japonicus, which can be found off the coasts of Korea, China, Japan, and Russia. This particular species most commonly is used in traditional dishes and is divided into 3 groups based on the color: red, green, or black. The price and taste of sea cucumbers varies based on the color, with red being the most expensive.² The body wall of the sea cucumber is cleaned, repeatedly boiled, and dried until edible. It is considered a delicacy, not only in food but also in pharmaceutical forms, as it is comprised of a variety of vitamins, minerals, and other nutrients that are thought to provide anticancer, anticoagulant, antioxidant, antifungal, and anti-inflammatory properties. Components of the body wall include collagen, mucopolysaccharides, peptides, gelatin, glycosaminoglycans, glycosides (including various holotoxins), hydroxylates, saponins, and fatty acids.² The regenerative properties of the sea cucumber also are important in future biomedical developments.

Toxic Properties

Although sea cucumbers have proven to have many beneficial properties, at least 30 species also produce potent toxins that pose a danger to both humans and other wildlife.³ The toxins are collectively referred to as holothurin; however, specific species actually produce a variety of holothurin toxins with unique chemical structures. Each toxin is a variation of a specific triterpene glycoside called saponins, which are common glycosides in the plant world. Holothurin was the first saponin to be found in animals. The only animals known to contain holothurin are the echinoderms, including sea cucumbers and sea stars.¹ Holothurins A and B are the 2 groups of holothurin toxins produced specifically by sea cucumbers. The toxins are composed of roughly 60% glycosides and pigment; 30% free amino acids (alanine, arginine, cysteine, glycine, glutamic acid, histidine, serine, and valine); 5% to 10% insoluble proteins; and 1% cholesterol, salts, and polypeptides.³

Holothurins are concentrated in granules within specialized structures of the sea cucumber called Cuvierian tubules, which freely float in the posterior coelomic cavity of the sea cucumber and are attached at the base of the respiratory tree. It is with these tubules that sea cucumbers utilize a unique defensive mechanism. Upon disturbance, the sea cucumber will turn its posterior end to the threat and squeeze its body in a series of violent contractions, inducing a tear in the cloacal wall.⁴ The tubules pass through this tear, are autotomized from the attachment point at the respiratory tree, and are finally expelled through the anus onto the predator and into the surrounding waters. The tubules are both sticky on contact and poisonous due to the holothurin, allowing the sea cucumber to crawl away from the threat unscathed. Over time, the tubules will regenerate, allowing the sea cucumber to protect itself again in the face of future danger.

Aside from direct disturbance by a threat, sea cucumbers also are known to undergo evisceration due to high temperatures and oxygen deficiency.³ Species that lack Cuvierian tubules can still produce holothurin toxins, though the toxins are secreted onto the outer surface of the body wall and mainly pose a risk with direct contact undiluted by seawater.⁵ The toxin induces a neural blockade in other sea creatures through its interaction with ion channels. On Asian islands, sea cucumbers have been exploited for this ability and commonly are thrown into tidal pools by fishermen to paralyze fish for easier capture.¹

Effects on Human Skin

In humans, the holothurin toxins of sea cucumbers cause an acute irritant dermatitis upon contact with the skin.⁶ Fishermen or divers handling sea cucumbers without gloves may present with an irritant contact dermatitis characterized by marked erythema and swelling (Figure 2).^6-8 Additionally, holothurin toxins can cause irritation of the mucous membranes of the eyes and mouth. Contact with the mucous membranes of the eyes can induce a painful conjunctivitis that may result in blindness.^6,8 Ingestion of large quantities of sea cucumber can produce an anticoagulant effect, and toxins in some species act similar to cardiac glycosides.^3,9

In addition to their own toxins, sea cucumbers also can secrete undigested nematocysts of previously consumed cnidarians through the integument.^7,10 In this case, the result of direct contact with the body wall is similar to a jellyfish sting in addition to the irritant contact dermatitis caused by the holothurin toxin.

Treatment and Prevention

Irritant dermatitis resulting from contact with a holothurin toxin is first treated with cleansing of the affected area at the time of exposure with generous amounts of seawater or preferably hot seawater and soap. Most marine toxins are inactivated by heat, but holothurin is partially heat stable. Vinegar or isopropyl alcohol also have been used.⁹ The result is removal of the slime containing the holothurin toxin rather than deactivation of the toxin. Although this alone may relieve symptoms, dermatitis also may be addressed with topical anesthetics, corticosteroids, or, if a severe reaction has occurred, systemic steroids.⁹

Conjunctivitis should be addressed with copious irrigation with tap water and topical anesthesia. Following proper irrigation, providers may choose to follow up with fluorescein staining to rule out corneal injury.¹⁰

The dermatologic effects of holothurin toxins can be prevented with the use of gloves and diving masks or goggles. Proper protective wear should be utilized not only when directly handling sea cucumbers but also when swimming in water where sea cucumbers may be present. Systemic toxicity can be prevented by proper cooking, as holothurin toxins are only partially heat resistant and also are hydrolyzed into nontoxic products by gastric acid. Additionally, the species of the sea cucumber should be confirmed prior to consumption, as edible species are known to contain less toxin.¹

Conclusion

Although sea cucumbers have ecologic, culinary, and pharmaceutical value, they also can pose a threat to both humans and wildlife. The holothurin toxins produced by sea cucumbers cause a painful contact dermatitis and can lead to conjunctivitis and even blindness following eye exposure. Although the toxin is broken down into nontoxic metabolites by gastric acid, large amounts of potent variants can induce systemic effects. Individuals who come in contact with sea cucumbers, such as fishermen and divers, should utilize proper protection including gloves and protective eyewear.

Sea cucumbers—commonly known as trepang in Indonesia, namako in Japan, and hai shen in China, where they are treasured as a food delicacy—are sea creatures belonging to the phylum Echinodermata, class Holothuridea, and family Cucumariidae . ^1,2 They are an integral part of a variety of marine habitats, serving as cleaners as they filter through sediment for nutrients. They can be found on the ocean floor under hundreds of feet of water or in shallow sandy waters along the coast, but they most commonly are found living among coral reefs. Sea cucumbers look just as they sound—shaped like cucumbers or sausages, ranging from under 1 inch to upwards of 6 feet in length depending on the specific species (Figure 1). They have a group of tentacles around the mouth used for filtering sediment, and they move about the ocean floor on tubular feet protruding through the body wall, similar to a sea star.

Beneficial Properties and Cultural Relevance

Although more than 1200 species of sea cucumbers have been identified thus far, only about 20 of these are edible.² The most common of the edible species is Stichopus japonicus, which can be found off the coasts of Korea, China, Japan, and Russia. This particular species most commonly is used in traditional dishes and is divided into 3 groups based on the color: red, green, or black. The price and taste of sea cucumbers varies based on the color, with red being the most expensive.² The body wall of the sea cucumber is cleaned, repeatedly boiled, and dried until edible. It is considered a delicacy, not only in food but also in pharmaceutical forms, as it is comprised of a variety of vitamins, minerals, and other nutrients that are thought to provide anticancer, anticoagulant, antioxidant, antifungal, and anti-inflammatory properties. Components of the body wall include collagen, mucopolysaccharides, peptides, gelatin, glycosaminoglycans, glycosides (including various holotoxins), hydroxylates, saponins, and fatty acids.² The regenerative properties of the sea cucumber also are important in future biomedical developments.

Toxic Properties

Although sea cucumbers have proven to have many beneficial properties, at least 30 species also produce potent toxins that pose a danger to both humans and other wildlife.³ The toxins are collectively referred to as holothurin; however, specific species actually produce a variety of holothurin toxins with unique chemical structures. Each toxin is a variation of a specific triterpene glycoside called saponins, which are common glycosides in the plant world. Holothurin was the first saponin to be found in animals. The only animals known to contain holothurin are the echinoderms, including sea cucumbers and sea stars.¹ Holothurins A and B are the 2 groups of holothurin toxins produced specifically by sea cucumbers. The toxins are composed of roughly 60% glycosides and pigment; 30% free amino acids (alanine, arginine, cysteine, glycine, glutamic acid, histidine, serine, and valine); 5% to 10% insoluble proteins; and 1% cholesterol, salts, and polypeptides.³

Holothurins are concentrated in granules within specialized structures of the sea cucumber called Cuvierian tubules, which freely float in the posterior coelomic cavity of the sea cucumber and are attached at the base of the respiratory tree. It is with these tubules that sea cucumbers utilize a unique defensive mechanism. Upon disturbance, the sea cucumber will turn its posterior end to the threat and squeeze its body in a series of violent contractions, inducing a tear in the cloacal wall.⁴ The tubules pass through this tear, are autotomized from the attachment point at the respiratory tree, and are finally expelled through the anus onto the predator and into the surrounding waters. The tubules are both sticky on contact and poisonous due to the holothurin, allowing the sea cucumber to crawl away from the threat unscathed. Over time, the tubules will regenerate, allowing the sea cucumber to protect itself again in the face of future danger.

Aside from direct disturbance by a threat, sea cucumbers also are known to undergo evisceration due to high temperatures and oxygen deficiency.³ Species that lack Cuvierian tubules can still produce holothurin toxins, though the toxins are secreted onto the outer surface of the body wall and mainly pose a risk with direct contact undiluted by seawater.⁵ The toxin induces a neural blockade in other sea creatures through its interaction with ion channels. On Asian islands, sea cucumbers have been exploited for this ability and commonly are thrown into tidal pools by fishermen to paralyze fish for easier capture.¹

Effects on Human Skin

In humans, the holothurin toxins of sea cucumbers cause an acute irritant dermatitis upon contact with the skin.⁶ Fishermen or divers handling sea cucumbers without gloves may present with an irritant contact dermatitis characterized by marked erythema and swelling (Figure 2).^6-8 Additionally, holothurin toxins can cause irritation of the mucous membranes of the eyes and mouth. Contact with the mucous membranes of the eyes can induce a painful conjunctivitis that may result in blindness.^6,8 Ingestion of large quantities of sea cucumber can produce an anticoagulant effect, and toxins in some species act similar to cardiac glycosides.^3,9

In addition to their own toxins, sea cucumbers also can secrete undigested nematocysts of previously consumed cnidarians through the integument.^7,10 In this case, the result of direct contact with the body wall is similar to a jellyfish sting in addition to the irritant contact dermatitis caused by the holothurin toxin.

Treatment and Prevention

Irritant dermatitis resulting from contact with a holothurin toxin is first treated with cleansing of the affected area at the time of exposure with generous amounts of seawater or preferably hot seawater and soap. Most marine toxins are inactivated by heat, but holothurin is partially heat stable. Vinegar or isopropyl alcohol also have been used.⁹ The result is removal of the slime containing the holothurin toxin rather than deactivation of the toxin. Although this alone may relieve symptoms, dermatitis also may be addressed with topical anesthetics, corticosteroids, or, if a severe reaction has occurred, systemic steroids.⁹

Conjunctivitis should be addressed with copious irrigation with tap water and topical anesthesia. Following proper irrigation, providers may choose to follow up with fluorescein staining to rule out corneal injury.¹⁰

The dermatologic effects of holothurin toxins can be prevented with the use of gloves and diving masks or goggles. Proper protective wear should be utilized not only when directly handling sea cucumbers but also when swimming in water where sea cucumbers may be present. Systemic toxicity can be prevented by proper cooking, as holothurin toxins are only partially heat resistant and also are hydrolyzed into nontoxic products by gastric acid. Additionally, the species of the sea cucumber should be confirmed prior to consumption, as edible species are known to contain less toxin.¹

Conclusion

Although sea cucumbers have ecologic, culinary, and pharmaceutical value, they also can pose a threat to both humans and wildlife. The holothurin toxins produced by sea cucumbers cause a painful contact dermatitis and can lead to conjunctivitis and even blindness following eye exposure. Although the toxin is broken down into nontoxic metabolites by gastric acid, large amounts of potent variants can induce systemic effects. Individuals who come in contact with sea cucumbers, such as fishermen and divers, should utilize proper protection including gloves and protective eyewear.

Sea cucumbers—commonly known as trepang in Indonesia, namako in Japan, and hai shen in China, where they are treasured as a food delicacy—are sea creatures belonging to the phylum Echinodermata, class Holothuridea, and family Cucumariidae . ^1,2 They are an integral part of a variety of marine habitats, serving as cleaners as they filter through sediment for nutrients. They can be found on the ocean floor under hundreds of feet of water or in shallow sandy waters along the coast, but they most commonly are found living among coral reefs. Sea cucumbers look just as they sound—shaped like cucumbers or sausages, ranging from under 1 inch to upwards of 6 feet in length depending on the specific species (Figure 1). They have a group of tentacles around the mouth used for filtering sediment, and they move about the ocean floor on tubular feet protruding through the body wall, similar to a sea star.

Beneficial Properties and Cultural Relevance

Although more than 1200 species of sea cucumbers have been identified thus far, only about 20 of these are edible.² The most common of the edible species is Stichopus japonicus, which can be found off the coasts of Korea, China, Japan, and Russia. This particular species most commonly is used in traditional dishes and is divided into 3 groups based on the color: red, green, or black. The price and taste of sea cucumbers varies based on the color, with red being the most expensive.² The body wall of the sea cucumber is cleaned, repeatedly boiled, and dried until edible. It is considered a delicacy, not only in food but also in pharmaceutical forms, as it is comprised of a variety of vitamins, minerals, and other nutrients that are thought to provide anticancer, anticoagulant, antioxidant, antifungal, and anti-inflammatory properties. Components of the body wall include collagen, mucopolysaccharides, peptides, gelatin, glycosaminoglycans, glycosides (including various holotoxins), hydroxylates, saponins, and fatty acids.² The regenerative properties of the sea cucumber also are important in future biomedical developments.

Toxic Properties

Although sea cucumbers have proven to have many beneficial properties, at least 30 species also produce potent toxins that pose a danger to both humans and other wildlife.³ The toxins are collectively referred to as holothurin; however, specific species actually produce a variety of holothurin toxins with unique chemical structures. Each toxin is a variation of a specific triterpene glycoside called saponins, which are common glycosides in the plant world. Holothurin was the first saponin to be found in animals. The only animals known to contain holothurin are the echinoderms, including sea cucumbers and sea stars.¹ Holothurins A and B are the 2 groups of holothurin toxins produced specifically by sea cucumbers. The toxins are composed of roughly 60% glycosides and pigment; 30% free amino acids (alanine, arginine, cysteine, glycine, glutamic acid, histidine, serine, and valine); 5% to 10% insoluble proteins; and 1% cholesterol, salts, and polypeptides.³

Holothurins are concentrated in granules within specialized structures of the sea cucumber called Cuvierian tubules, which freely float in the posterior coelomic cavity of the sea cucumber and are attached at the base of the respiratory tree. It is with these tubules that sea cucumbers utilize a unique defensive mechanism. Upon disturbance, the sea cucumber will turn its posterior end to the threat and squeeze its body in a series of violent contractions, inducing a tear in the cloacal wall.⁴ The tubules pass through this tear, are autotomized from the attachment point at the respiratory tree, and are finally expelled through the anus onto the predator and into the surrounding waters. The tubules are both sticky on contact and poisonous due to the holothurin, allowing the sea cucumber to crawl away from the threat unscathed. Over time, the tubules will regenerate, allowing the sea cucumber to protect itself again in the face of future danger.

Aside from direct disturbance by a threat, sea cucumbers also are known to undergo evisceration due to high temperatures and oxygen deficiency.³ Species that lack Cuvierian tubules can still produce holothurin toxins, though the toxins are secreted onto the outer surface of the body wall and mainly pose a risk with direct contact undiluted by seawater.⁵ The toxin induces a neural blockade in other sea creatures through its interaction with ion channels. On Asian islands, sea cucumbers have been exploited for this ability and commonly are thrown into tidal pools by fishermen to paralyze fish for easier capture.¹

Effects on Human Skin

In humans, the holothurin toxins of sea cucumbers cause an acute irritant dermatitis upon contact with the skin.⁶ Fishermen or divers handling sea cucumbers without gloves may present with an irritant contact dermatitis characterized by marked erythema and swelling (Figure 2).^6-8 Additionally, holothurin toxins can cause irritation of the mucous membranes of the eyes and mouth. Contact with the mucous membranes of the eyes can induce a painful conjunctivitis that may result in blindness.^6,8 Ingestion of large quantities of sea cucumber can produce an anticoagulant effect, and toxins in some species act similar to cardiac glycosides.^3,9

In addition to their own toxins, sea cucumbers also can secrete undigested nematocysts of previously consumed cnidarians through the integument.^7,10 In this case, the result of direct contact with the body wall is similar to a jellyfish sting in addition to the irritant contact dermatitis caused by the holothurin toxin.

Treatment and Prevention

Irritant dermatitis resulting from contact with a holothurin toxin is first treated with cleansing of the affected area at the time of exposure with generous amounts of seawater or preferably hot seawater and soap. Most marine toxins are inactivated by heat, but holothurin is partially heat stable. Vinegar or isopropyl alcohol also have been used.⁹ The result is removal of the slime containing the holothurin toxin rather than deactivation of the toxin. Although this alone may relieve symptoms, dermatitis also may be addressed with topical anesthetics, corticosteroids, or, if a severe reaction has occurred, systemic steroids.⁹

Conjunctivitis should be addressed with copious irrigation with tap water and topical anesthesia. Following proper irrigation, providers may choose to follow up with fluorescein staining to rule out corneal injury.¹⁰

The dermatologic effects of holothurin toxins can be prevented with the use of gloves and diving masks or goggles. Proper protective wear should be utilized not only when directly handling sea cucumbers but also when swimming in water where sea cucumbers may be present. Systemic toxicity can be prevented by proper cooking, as holothurin toxins are only partially heat resistant and also are hydrolyzed into nontoxic products by gastric acid. Additionally, the species of the sea cucumber should be confirmed prior to consumption, as edible species are known to contain less toxin.¹

Conclusion

Although sea cucumbers have ecologic, culinary, and pharmaceutical value, they also can pose a threat to both humans and wildlife. The holothurin toxins produced by sea cucumbers cause a painful contact dermatitis and can lead to conjunctivitis and even blindness following eye exposure. Although the toxin is broken down into nontoxic metabolites by gastric acid, large amounts of potent variants can induce systemic effects. Individuals who come in contact with sea cucumbers, such as fishermen and divers, should utilize proper protection including gloves and protective eyewear.

To the Editor:

Phacomatosis pigmentokeratotica (PPK) is a rare epidermal nevus syndrome complicated by multiple extracutaneous anomalies, including skeletal defects and neurologic anomalies. Less common associations include lateral curvature of the spine and hyperhidrosis. We present a patient with PPK and unilateral Raynaud phenomenon in addition to a segmental distribution of melanocytic nevi, hyperhidrosis, and scoliosis.

A 9-year-old girl was born with a yellow-orange alopecic plaque on the right side of the scalp (Figure 1). There also were 2 large, irregularly pigmented patches localized on the right side of the upper back and buttock. Over 3 years, numerous papular nevi developed within these pigmented patches and were diagnosed as speckled lentiginous nevi (Figure 2). In addition, numerous nevi of various sizes affected the right face, right shoulder, right arm (Figure 3), and right neck and were clearly demarcated along the midline. Several nevi also were noted within the nevus sebaceous on the right scalp. These skin lesions expanded progressively with age. At 6 years of age, she was diagnosed with hyperhidrosis of the right half of the body, which was most pronounced on the face. Raynaud phenomenon restricted to the right hand also was noted (Figure 4). Upon cold exposure, the digits become pale white, cold, and numb; then blue; and finally red. She lacked other features of connective tissue disease, and autoantibody testing was negative. She also was noted to have an abnormal lateral curvature of the spine (scoliosis). Auditory, ocular, and neurologic examinations were normal. Cranial and cerebral magnetic resonance imaging showed no central nervous system abnormalities. Her family history was negative for nevus spilus, nevus sebaceous, and neurofibromatosis. The clinical findings in our patient led to the diagnosis of PPK.

Raynaud phenomenon involving only the right hand was a unique finding in our patient. In 3 years of follow-up, our patient developed no evidence of connective tissue disease or other systemic illness. We speculate that Raynaud phenomenon of the right hand along with hyperhidrosis of the right side of the body could be a result of dysfunction of the autonomic nervous system. We propose that Raynaud phenomenon represents an unusual manifestation of PPK and may broaden the spectrum of extracutaneous anomalies associated with the disease. The finding of segmental nevi outside of the confines of the nevus spilus was another unusual manifestation of mosaicism.

To the Editor:

Phacomatosis pigmentokeratotica (PPK) is a rare epidermal nevus syndrome complicated by multiple extracutaneous anomalies, including skeletal defects and neurologic anomalies. Less common associations include lateral curvature of the spine and hyperhidrosis. We present a patient with PPK and unilateral Raynaud phenomenon in addition to a segmental distribution of melanocytic nevi, hyperhidrosis, and scoliosis.

A 9-year-old girl was born with a yellow-orange alopecic plaque on the right side of the scalp (Figure 1). There also were 2 large, irregularly pigmented patches localized on the right side of the upper back and buttock. Over 3 years, numerous papular nevi developed within these pigmented patches and were diagnosed as speckled lentiginous nevi (Figure 2). In addition, numerous nevi of various sizes affected the right face, right shoulder, right arm (Figure 3), and right neck and were clearly demarcated along the midline. Several nevi also were noted within the nevus sebaceous on the right scalp. These skin lesions expanded progressively with age. At 6 years of age, she was diagnosed with hyperhidrosis of the right half of the body, which was most pronounced on the face. Raynaud phenomenon restricted to the right hand also was noted (Figure 4). Upon cold exposure, the digits become pale white, cold, and numb; then blue; and finally red. She lacked other features of connective tissue disease, and autoantibody testing was negative. She also was noted to have an abnormal lateral curvature of the spine (scoliosis). Auditory, ocular, and neurologic examinations were normal. Cranial and cerebral magnetic resonance imaging showed no central nervous system abnormalities. Her family history was negative for nevus spilus, nevus sebaceous, and neurofibromatosis. The clinical findings in our patient led to the diagnosis of PPK.

Raynaud phenomenon involving only the right hand was a unique finding in our patient. In 3 years of follow-up, our patient developed no evidence of connective tissue disease or other systemic illness. We speculate that Raynaud phenomenon of the right hand along with hyperhidrosis of the right side of the body could be a result of dysfunction of the autonomic nervous system. We propose that Raynaud phenomenon represents an unusual manifestation of PPK and may broaden the spectrum of extracutaneous anomalies associated with the disease. The finding of segmental nevi outside of the confines of the nevus spilus was another unusual manifestation of mosaicism.

To the Editor:

Phacomatosis pigmentokeratotica (PPK) is a rare epidermal nevus syndrome complicated by multiple extracutaneous anomalies, including skeletal defects and neurologic anomalies. Less common associations include lateral curvature of the spine and hyperhidrosis. We present a patient with PPK and unilateral Raynaud phenomenon in addition to a segmental distribution of melanocytic nevi, hyperhidrosis, and scoliosis.

A 9-year-old girl was born with a yellow-orange alopecic plaque on the right side of the scalp (Figure 1). There also were 2 large, irregularly pigmented patches localized on the right side of the upper back and buttock. Over 3 years, numerous papular nevi developed within these pigmented patches and were diagnosed as speckled lentiginous nevi (Figure 2). In addition, numerous nevi of various sizes affected the right face, right shoulder, right arm (Figure 3), and right neck and were clearly demarcated along the midline. Several nevi also were noted within the nevus sebaceous on the right scalp. These skin lesions expanded progressively with age. At 6 years of age, she was diagnosed with hyperhidrosis of the right half of the body, which was most pronounced on the face. Raynaud phenomenon restricted to the right hand also was noted (Figure 4). Upon cold exposure, the digits become pale white, cold, and numb; then blue; and finally red. She lacked other features of connective tissue disease, and autoantibody testing was negative. She also was noted to have an abnormal lateral curvature of the spine (scoliosis). Auditory, ocular, and neurologic examinations were normal. Cranial and cerebral magnetic resonance imaging showed no central nervous system abnormalities. Her family history was negative for nevus spilus, nevus sebaceous, and neurofibromatosis. The clinical findings in our patient led to the diagnosis of PPK.

Raynaud phenomenon involving only the right hand was a unique finding in our patient. In 3 years of follow-up, our patient developed no evidence of connective tissue disease or other systemic illness. We speculate that Raynaud phenomenon of the right hand along with hyperhidrosis of the right side of the body could be a result of dysfunction of the autonomic nervous system. We propose that Raynaud phenomenon represents an unusual manifestation of PPK and may broaden the spectrum of extracutaneous anomalies associated with the disease. The finding of segmental nevi outside of the confines of the nevus spilus was another unusual manifestation of mosaicism.

The Diagnosis: Keratoderma Climactericum 

Keratoderma climactericum was first reported in 1934 by Haxthausen¹ as nonpruritic circumscribed hyperkeratosis located mainly on the palms and soles. The initial eruption was described as discrete lesions with an oval or round shape that progressed to less-defined, confluent, hyperkeratotic patches with fissures.¹ Keratoderma climactericum also may be referred to as Haxthausen disease and is considered an acquired palmoplantar keratoderma.² 

Keratoderma climactericum is a rare dermatologic disorder that presents in women of menopausal age who have no family or personal history of skin disease. Keratoderma climactericum is associated with hypertension and obesity.² Keratotic lesions usually first occur on the plantar surfaces with eventual development of fissuring and hyperkeratosis that causes painful walking. The keratotic lesions on the plantar surfaces often are nonpruritic and gradually become confluent over time. As the disease progresses, keratotic lesions appear on the central palms, which can lead to confluent hyperkeratosis on the palmar surfaces (Figure 1).² The exact mechanism of keratoderma climactericum has not been described but is believed to be due to hormonal dysregulation.²  

Treatment options for keratoderma climactericum include salicylic acid, emollients, oral retinoids, urea ointments, estriol cream, and topical steroids.^5,6 Our patient was prescribed acitretin 25 mg daily and ammonium lactate to apply topically as needed for dry skin. Five months after the initial presentation, fissures and dry skin on the bilateral soles were still present. Ammonium lactate was discontinued, and the patient was prescribed urea cream 40%. Fifteen months after the initial presentation, the patient reported substantial improvement on the hands and feet and noted that she no longer needed the urea cream. Physical examination revealed no presence of hyperkeratosis or fissuring on the palms (Figure 2), and mild hyperkeratosis was present on the plantar surfaces of the feet (Figure 3). The patient continued to use acitretin to prevent disease relapse.  

The Diagnosis: Keratoderma Climactericum 

Keratoderma climactericum was first reported in 1934 by Haxthausen¹ as nonpruritic circumscribed hyperkeratosis located mainly on the palms and soles. The initial eruption was described as discrete lesions with an oval or round shape that progressed to less-defined, confluent, hyperkeratotic patches with fissures.¹ Keratoderma climactericum also may be referred to as Haxthausen disease and is considered an acquired palmoplantar keratoderma.² 

Keratoderma climactericum is a rare dermatologic disorder that presents in women of menopausal age who have no family or personal history of skin disease. Keratoderma climactericum is associated with hypertension and obesity.² Keratotic lesions usually first occur on the plantar surfaces with eventual development of fissuring and hyperkeratosis that causes painful walking. The keratotic lesions on the plantar surfaces often are nonpruritic and gradually become confluent over time. As the disease progresses, keratotic lesions appear on the central palms, which can lead to confluent hyperkeratosis on the palmar surfaces (Figure 1).² The exact mechanism of keratoderma climactericum has not been described but is believed to be due to hormonal dysregulation.²  

Treatment options for keratoderma climactericum include salicylic acid, emollients, oral retinoids, urea ointments, estriol cream, and topical steroids.^5,6 Our patient was prescribed acitretin 25 mg daily and ammonium lactate to apply topically as needed for dry skin. Five months after the initial presentation, fissures and dry skin on the bilateral soles were still present. Ammonium lactate was discontinued, and the patient was prescribed urea cream 40%. Fifteen months after the initial presentation, the patient reported substantial improvement on the hands and feet and noted that she no longer needed the urea cream. Physical examination revealed no presence of hyperkeratosis or fissuring on the palms (Figure 2), and mild hyperkeratosis was present on the plantar surfaces of the feet (Figure 3). The patient continued to use acitretin to prevent disease relapse.  

The Diagnosis: Keratoderma Climactericum 

Keratoderma climactericum was first reported in 1934 by Haxthausen¹ as nonpruritic circumscribed hyperkeratosis located mainly on the palms and soles. The initial eruption was described as discrete lesions with an oval or round shape that progressed to less-defined, confluent, hyperkeratotic patches with fissures.¹ Keratoderma climactericum also may be referred to as Haxthausen disease and is considered an acquired palmoplantar keratoderma.² 

Keratoderma climactericum is a rare dermatologic disorder that presents in women of menopausal age who have no family or personal history of skin disease. Keratoderma climactericum is associated with hypertension and obesity.² Keratotic lesions usually first occur on the plantar surfaces with eventual development of fissuring and hyperkeratosis that causes painful walking. The keratotic lesions on the plantar surfaces often are nonpruritic and gradually become confluent over time. As the disease progresses, keratotic lesions appear on the central palms, which can lead to confluent hyperkeratosis on the palmar surfaces (Figure 1).² The exact mechanism of keratoderma climactericum has not been described but is believed to be due to hormonal dysregulation.²  

Treatment options for keratoderma climactericum include salicylic acid, emollients, oral retinoids, urea ointments, estriol cream, and topical steroids.^5,6 Our patient was prescribed acitretin 25 mg daily and ammonium lactate to apply topically as needed for dry skin. Five months after the initial presentation, fissures and dry skin on the bilateral soles were still present. Ammonium lactate was discontinued, and the patient was prescribed urea cream 40%. Fifteen months after the initial presentation, the patient reported substantial improvement on the hands and feet and noted that she no longer needed the urea cream. Physical examination revealed no presence of hyperkeratosis or fissuring on the palms (Figure 2), and mild hyperkeratosis was present on the plantar surfaces of the feet (Figure 3). The patient continued to use acitretin to prevent disease relapse.  

The Diagnosis: Phytophotodermatitis 

A  more detailed patient history revealed that there was beer with limes on the boat, but the partygoers neglected to bring a knife. The patient volunteered to tear the limes apart with his bare hands. Because he was clad only in swim trunks, lime juice splattered over various regions of his body. 

Phytophotodermatitis is a phototoxic blistering rash that follows topical exposure to plant-derived furocoumarins and sunlight. (Figure) Furocoumarins are photosensitizing substances produced by certain plants, possibly as a defense mechanism against predators.¹ They cause a nonimmunologic phototoxic reaction when deposited on the skin and exposed to UVA radiation. Exposure to limes is the most common precipitant of phytophotodermatitis, but other potential culprits include lemons, grapefruit, figs, carrots, parsnips, celery, and dill.²  

Lesions associated with phytophotodermatitis classically present as painful erythematous patches and bullae in regions of furocoumarin exposure. Affected areas are well demarcated and irregularly shaped and heal with a characteristic hyperpigmented rim. They often have a downward streak pattern from the dripping juice.³ If the furocoumarins are transferred by touch, lesions can appear in the shape of handprints, which may raise alarms for physical abuse in children.⁴ 

Photochemical reactions caused by activated furocoumarins cross-link nuclear DNA and damage cell membranes. These changes lead to cellular death resulting in edema and destruction of the epidermis. Other effects include an increase in keratin and thickening of the stratum corneum. The hyperpigmentation is a result of increased concentration of melanosomes and stimulation of melanocytes by activated furocoumarins.⁵ 

Management of phytophotodermatitis depends on the severity of skin injury. Mild cases may not require any treatment, whereas the most severe ones require admission to a burn unit for wound care. Anti-inflammatory medications are the mainstay of therapy. Our patient was prescribed desonide cream 0.05% for application to the affected areas. Sunscreen should be applied to prevent worsening of hyperpigmentation, which may take months to years to fade naturally. If hyperpigmentation is cosmetically troubling to the patient, bleaching agents such as hydroquinone and retinoids or Nd:YAG laser can be used to accelerate the resolution of pigment.⁵ 

Phototoxicity differs from less common photoallergic reactions caused by preformed antibodies or a delayed cell-mediated response to a trigger. The classic presentation of photoallergy is apruritic, inflammatory, bullous eruption in a sensitized individual.⁶ Allergic contact dermatitis more commonly is associated with pruritus than pain, and it presents as a papulovesicular eruption that evolves into lichenified plaques.⁷ Porphyria cutanea tarda would likely be accompanied by other cutaneous features such as hypertrichosis and sclerodermoid plaques with dystrophic calcification, in addition to wine-colored urine-containing porphyrins.⁸ Bullous fixed drug eruptions develop within 48 hours of exposure to a causative agent. The patient typically would experience pruritus and burning at the site of clearly demarcated erythematous lesions that healed with hyperpigmentation.⁹ Lesions of bullous lupus erythematosus may appear in areas without sun exposure, and they would be more likely to leave behind hypopigmentation rather than hyperpigmentation.¹⁰ 

The Diagnosis: Phytophotodermatitis 

A  more detailed patient history revealed that there was beer with limes on the boat, but the partygoers neglected to bring a knife. The patient volunteered to tear the limes apart with his bare hands. Because he was clad only in swim trunks, lime juice splattered over various regions of his body. 

Phytophotodermatitis is a phototoxic blistering rash that follows topical exposure to plant-derived furocoumarins and sunlight. (Figure) Furocoumarins are photosensitizing substances produced by certain plants, possibly as a defense mechanism against predators.¹ They cause a nonimmunologic phototoxic reaction when deposited on the skin and exposed to UVA radiation. Exposure to limes is the most common precipitant of phytophotodermatitis, but other potential culprits include lemons, grapefruit, figs, carrots, parsnips, celery, and dill.²  

Lesions associated with phytophotodermatitis classically present as painful erythematous patches and bullae in regions of furocoumarin exposure. Affected areas are well demarcated and irregularly shaped and heal with a characteristic hyperpigmented rim. They often have a downward streak pattern from the dripping juice.³ If the furocoumarins are transferred by touch, lesions can appear in the shape of handprints, which may raise alarms for physical abuse in children.⁴ 

Photochemical reactions caused by activated furocoumarins cross-link nuclear DNA and damage cell membranes. These changes lead to cellular death resulting in edema and destruction of the epidermis. Other effects include an increase in keratin and thickening of the stratum corneum. The hyperpigmentation is a result of increased concentration of melanosomes and stimulation of melanocytes by activated furocoumarins.⁵ 

Management of phytophotodermatitis depends on the severity of skin injury. Mild cases may not require any treatment, whereas the most severe ones require admission to a burn unit for wound care. Anti-inflammatory medications are the mainstay of therapy. Our patient was prescribed desonide cream 0.05% for application to the affected areas. Sunscreen should be applied to prevent worsening of hyperpigmentation, which may take months to years to fade naturally. If hyperpigmentation is cosmetically troubling to the patient, bleaching agents such as hydroquinone and retinoids or Nd:YAG laser can be used to accelerate the resolution of pigment.⁵ 

Phototoxicity differs from less common photoallergic reactions caused by preformed antibodies or a delayed cell-mediated response to a trigger. The classic presentation of photoallergy is apruritic, inflammatory, bullous eruption in a sensitized individual.⁶ Allergic contact dermatitis more commonly is associated with pruritus than pain, and it presents as a papulovesicular eruption that evolves into lichenified plaques.⁷ Porphyria cutanea tarda would likely be accompanied by other cutaneous features such as hypertrichosis and sclerodermoid plaques with dystrophic calcification, in addition to wine-colored urine-containing porphyrins.⁸ Bullous fixed drug eruptions develop within 48 hours of exposure to a causative agent. The patient typically would experience pruritus and burning at the site of clearly demarcated erythematous lesions that healed with hyperpigmentation.⁹ Lesions of bullous lupus erythematosus may appear in areas without sun exposure, and they would be more likely to leave behind hypopigmentation rather than hyperpigmentation.¹⁰ 

The Diagnosis: Phytophotodermatitis 

A  more detailed patient history revealed that there was beer with limes on the boat, but the partygoers neglected to bring a knife. The patient volunteered to tear the limes apart with his bare hands. Because he was clad only in swim trunks, lime juice splattered over various regions of his body. 

Phytophotodermatitis is a phototoxic blistering rash that follows topical exposure to plant-derived furocoumarins and sunlight. (Figure) Furocoumarins are photosensitizing substances produced by certain plants, possibly as a defense mechanism against predators.¹ They cause a nonimmunologic phototoxic reaction when deposited on the skin and exposed to UVA radiation. Exposure to limes is the most common precipitant of phytophotodermatitis, but other potential culprits include lemons, grapefruit, figs, carrots, parsnips, celery, and dill.²  

Lesions associated with phytophotodermatitis classically present as painful erythematous patches and bullae in regions of furocoumarin exposure. Affected areas are well demarcated and irregularly shaped and heal with a characteristic hyperpigmented rim. They often have a downward streak pattern from the dripping juice.³ If the furocoumarins are transferred by touch, lesions can appear in the shape of handprints, which may raise alarms for physical abuse in children.⁴ 

Photochemical reactions caused by activated furocoumarins cross-link nuclear DNA and damage cell membranes. These changes lead to cellular death resulting in edema and destruction of the epidermis. Other effects include an increase in keratin and thickening of the stratum corneum. The hyperpigmentation is a result of increased concentration of melanosomes and stimulation of melanocytes by activated furocoumarins.⁵ 

Management of phytophotodermatitis depends on the severity of skin injury. Mild cases may not require any treatment, whereas the most severe ones require admission to a burn unit for wound care. Anti-inflammatory medications are the mainstay of therapy. Our patient was prescribed desonide cream 0.05% for application to the affected areas. Sunscreen should be applied to prevent worsening of hyperpigmentation, which may take months to years to fade naturally. If hyperpigmentation is cosmetically troubling to the patient, bleaching agents such as hydroquinone and retinoids or Nd:YAG laser can be used to accelerate the resolution of pigment.⁵ 

Phototoxicity differs from less common photoallergic reactions caused by preformed antibodies or a delayed cell-mediated response to a trigger. The classic presentation of photoallergy is apruritic, inflammatory, bullous eruption in a sensitized individual.⁶ Allergic contact dermatitis more commonly is associated with pruritus than pain, and it presents as a papulovesicular eruption that evolves into lichenified plaques.⁷ Porphyria cutanea tarda would likely be accompanied by other cutaneous features such as hypertrichosis and sclerodermoid plaques with dystrophic calcification, in addition to wine-colored urine-containing porphyrins.⁸ Bullous fixed drug eruptions develop within 48 hours of exposure to a causative agent. The patient typically would experience pruritus and burning at the site of clearly demarcated erythematous lesions that healed with hyperpigmentation.⁹ Lesions of bullous lupus erythematosus may appear in areas without sun exposure, and they would be more likely to leave behind hypopigmentation rather than hyperpigmentation.¹⁰