Shedding Light on the Problem

A 49-year-old man presents to dermatology for evaluation of an itchy rash that manifested several months ago. Attempts to eradicate or ameliorate it—which have included topical and systemic steroids and oral antibiotics (minocycline)—have had no effect. A biopsy ordered by his primary care provider (PCP) showed nonspecific changes, termed “dermatitis” in the report.

The patient denies any history of atopy, such as seasonal allergies or eczema. His only medical problem is moderate hypertension, for which his PCP prescribed hydrochlorothiazide. He started taking the drug a few weeks before the rash appeared.

He claims to be in good health otherwise, with no weakness or weight loss. He has never smoked.

EXAMINATION

A bright red, blanchable, maculopapular rash is notably confined to the patient’s sun-exposed skin; it sharply spares the areas covered by clothing and the watch on his left wrist. His palms, soles, scalp, and face are also spared. No nail changes are noted.

Otherwise, the patient appears well and is able to rise from a seated position without difficulty. No nodes are palpable in the head or neck, and there is no organomegaly detected on abdominal examination.

What is the diagnosis?

Photosensitivity to hydrochlorothiazide was the obvious culprit, so the patient was advised to stop using that product (after consulting his PCP). He’ll remain off the medication for at least two months, then present for follow-up.

There are some potentially troubling items in the differential, particularly dermatomyositis (DM). Patients with DM may exhibit a sunburn-like rash, but they will additionally demonstrate muscle weakness and chronic fatigue. A significant proportion of their complaints are driven by an occult carcinoma (eg, stomach, lung, colon, breast). While it’s doubtful that this patient has DM, his follow-up may include a fresh biopsy, blood work, anteroposterior and lateral chest films, and possibly a colonoscopy.

Another item in the differential is lupus. However, the original biopsy yielded no suggestive findings (eg, interface dermatitis), nor did the patient have any complaints referable to the disease.

This case nicely demonstrates the concept that it is equally important to note which areas are affected by and spared by a skin condition. With that in mind, we can at least establish that sunlight is a major factor in the genesis of this rash. Unfortunately, that still leaves room for conjecture as to the diagnosis.

TAKE-HOME LEARNING POINTS

• Rashes confined to sun-exposed skin can be a symptom of systemic disease, such as lupus or dermatomyositis.
• Various drugs—including hydrochlorothiazide, NSAIDs, sulfas, and certain tetracyclines—can also cause photosensitivity reactions.
• Hydrochlorothiazide is one of the more common drugs to cause such a rash, which may take weeks to clear after cessation of use.
• If terminating hydrochlorothiazide doesn’t help, skin biopsy and labs (especially creatine kinase and immunoglobulins) are the next step in determining the problem.

A 49-year-old man presents to dermatology for evaluation of an itchy rash that manifested several months ago. Attempts to eradicate or ameliorate it—which have included topical and systemic steroids and oral antibiotics (minocycline)—have had no effect. A biopsy ordered by his primary care provider (PCP) showed nonspecific changes, termed “dermatitis” in the report.

The patient denies any history of atopy, such as seasonal allergies or eczema. His only medical problem is moderate hypertension, for which his PCP prescribed hydrochlorothiazide. He started taking the drug a few weeks before the rash appeared.

He claims to be in good health otherwise, with no weakness or weight loss. He has never smoked.

EXAMINATION

A bright red, blanchable, maculopapular rash is notably confined to the patient’s sun-exposed skin; it sharply spares the areas covered by clothing and the watch on his left wrist. His palms, soles, scalp, and face are also spared. No nail changes are noted.

Otherwise, the patient appears well and is able to rise from a seated position without difficulty. No nodes are palpable in the head or neck, and there is no organomegaly detected on abdominal examination.

What is the diagnosis?

Photosensitivity to hydrochlorothiazide was the obvious culprit, so the patient was advised to stop using that product (after consulting his PCP). He’ll remain off the medication for at least two months, then present for follow-up.

There are some potentially troubling items in the differential, particularly dermatomyositis (DM). Patients with DM may exhibit a sunburn-like rash, but they will additionally demonstrate muscle weakness and chronic fatigue. A significant proportion of their complaints are driven by an occult carcinoma (eg, stomach, lung, colon, breast). While it’s doubtful that this patient has DM, his follow-up may include a fresh biopsy, blood work, anteroposterior and lateral chest films, and possibly a colonoscopy.

Another item in the differential is lupus. However, the original biopsy yielded no suggestive findings (eg, interface dermatitis), nor did the patient have any complaints referable to the disease.

This case nicely demonstrates the concept that it is equally important to note which areas are affected by and spared by a skin condition. With that in mind, we can at least establish that sunlight is a major factor in the genesis of this rash. Unfortunately, that still leaves room for conjecture as to the diagnosis.

TAKE-HOME LEARNING POINTS

• Rashes confined to sun-exposed skin can be a symptom of systemic disease, such as lupus or dermatomyositis.
• Various drugs—including hydrochlorothiazide, NSAIDs, sulfas, and certain tetracyclines—can also cause photosensitivity reactions.
• Hydrochlorothiazide is one of the more common drugs to cause such a rash, which may take weeks to clear after cessation of use.
• If terminating hydrochlorothiazide doesn’t help, skin biopsy and labs (especially creatine kinase and immunoglobulins) are the next step in determining the problem.

A 49-year-old man presents to dermatology for evaluation of an itchy rash that manifested several months ago. Attempts to eradicate or ameliorate it—which have included topical and systemic steroids and oral antibiotics (minocycline)—have had no effect. A biopsy ordered by his primary care provider (PCP) showed nonspecific changes, termed “dermatitis” in the report.

The patient denies any history of atopy, such as seasonal allergies or eczema. His only medical problem is moderate hypertension, for which his PCP prescribed hydrochlorothiazide. He started taking the drug a few weeks before the rash appeared.

He claims to be in good health otherwise, with no weakness or weight loss. He has never smoked.

EXAMINATION

A bright red, blanchable, maculopapular rash is notably confined to the patient’s sun-exposed skin; it sharply spares the areas covered by clothing and the watch on his left wrist. His palms, soles, scalp, and face are also spared. No nail changes are noted.

Otherwise, the patient appears well and is able to rise from a seated position without difficulty. No nodes are palpable in the head or neck, and there is no organomegaly detected on abdominal examination.

What is the diagnosis?

Photosensitivity to hydrochlorothiazide was the obvious culprit, so the patient was advised to stop using that product (after consulting his PCP). He’ll remain off the medication for at least two months, then present for follow-up.

There are some potentially troubling items in the differential, particularly dermatomyositis (DM). Patients with DM may exhibit a sunburn-like rash, but they will additionally demonstrate muscle weakness and chronic fatigue. A significant proportion of their complaints are driven by an occult carcinoma (eg, stomach, lung, colon, breast). While it’s doubtful that this patient has DM, his follow-up may include a fresh biopsy, blood work, anteroposterior and lateral chest films, and possibly a colonoscopy.

Another item in the differential is lupus. However, the original biopsy yielded no suggestive findings (eg, interface dermatitis), nor did the patient have any complaints referable to the disease.

This case nicely demonstrates the concept that it is equally important to note which areas are affected by and spared by a skin condition. With that in mind, we can at least establish that sunlight is a major factor in the genesis of this rash. Unfortunately, that still leaves room for conjecture as to the diagnosis.

TAKE-HOME LEARNING POINTS

• Rashes confined to sun-exposed skin can be a symptom of systemic disease, such as lupus or dermatomyositis.
• Various drugs—including hydrochlorothiazide, NSAIDs, sulfas, and certain tetracyclines—can also cause photosensitivity reactions.
• Hydrochlorothiazide is one of the more common drugs to cause such a rash, which may take weeks to clear after cessation of use.
• If terminating hydrochlorothiazide doesn’t help, skin biopsy and labs (especially creatine kinase and immunoglobulins) are the next step in determining the problem.