A complete body examination failed to reveal any other lesions suggestive of a fungal infection. A blood count and urinalysis were within normal limits. She had no lymphadenopathy or hepatosplenomegaly. She was diagnosed with cutaneous larva migrans (CLM) given the clinical appearance of the lesions and the recent travel history.
Dr. Catalina Matiz
CLM is a zoonotic infection caused by several hookworms such as Ancylostoma braziliense, Ancylostoma caninum, and Uncinaria stenocephala, as well as human hookworms such as Ancylostoma duodenale and Necator americanus. The hookworms can be present in contaminated soils and sandy beaches on the coastal regions of South America, the Caribbean, the Southeastern United States, Southeast Asia, and Africa.1-5
It is a common disease in the tourist population visiting tropical countries because of exposure to the hookworms in the soil without use of proper foot protection.
The clinical features are of an erythematous linear serpiginous plaque that is pruritic and can progress from millimeters to centimeters in size within a few days to weeks. Vesicles and multiple tracks can also be seen. The most common locations are the feet, buttocks, and thighs.
The larvae in the soil come from eggs excreted in the feces of infected cats and dogs. The infection is caused by direct contact of the larvae with the stratum corneum of the skin creating a burrow and an inflammatory response that will cause erythema, edema, track formation, and pruritus.
Diagnosis is made clinically. Rarely, a skin biopsy is warranted. The differential diagnosis includes tinea pedis, granuloma annulare, larva currens, contact dermatitis, and herpes zoster.
Dr. Alix J. Valderrama
Tinea pedis is a fungal infection of the skin of the feet, commonly localized on the web spaces. The risk factors are a hot and humid environment, prolonged wear of occlusive footwear, excess sweating, and prolonged exposure to water.6 Diagnosis is confirmed by microscopic evaluation of skin scrapings with potassium hydroxide or a fungal culture. The infection is treated with topical antifungal creams and, in severe cases, systemic antifungals. Granuloma annulare is a benign chronic skin condition that presents with annular-shaped lesions. Its etiology is unknown. The lesions may be asymptomatic or mildly pruritic. Localized granuloma annulare typically presents as reddish-brown papules or plaques on the fingers, hands, elbows, dorsal feet, or ankles. The feature distinguishing granuloma annulare from other annular lesions is its absence of scale.
Allergic contact dermatitis is caused by skin exposure to an allergen and a secondary inflammatory response to this material on the skin causing inflammation, vesiculation, and pruritus. Lesions are treated with topical corticosteroids and avoidance of the allergen.
Herpes zoster is caused by a viral infection of the latent varicella-zoster virus. Its reactivation causes the presence of vesicles with an erythematous base that have a dermatomal distribution. The lesions are usually tender. Treatment is recommended to be started within 72 hours of the eruption with antivirals such as acyclovir or valacyclovir.
Cutaneous larva currens is caused by the cutaneous infection with Strongyloides stercoralis. In comparison with CLM, the lesions progress faster, at up to a centimeter within hours.
CLM is usually self-limited. If the patient has multiple lesions or more severe disease, oral albendazole or ivermectin can be prescribed. Other treatments, though not preferred, include freezing and topical thiabendazole solutions.
As our patient had several lesions, oral ivermectin was chosen as treatment and the lesions cleared within a week. Also, she was recommended to always wear shoes when walking on the beach.
Dr. Matiz is a pediatric dermatologist at Southern California Permanente Medical Group, San Diego. Dr. Valderrama is a pediatric dermatologist at Fundación Cardioinfantil, Bogota, Colombia.
References
1. Feldmeier H and Schuster A. Eur J Clin Microbiol Infect Dis. 2012 Jun;31(6):915-8.
2. Jacobson CC and Abel EA. J Am Acad Dermatol. 2007 Jun;56(6):1026-43.
3. Kincaid L et al. Travel Med Infect Dis. 2015 Sep-Oct;13(5):382-7.
4. Gill N et al. Adv Skin Wound Care. 2020 Jul;33(7):356-9.
5. Rodenas-Herranz T et al. Dermatol Ther. 2020 May;33(3):e13316.
6. Pramod K et al. In: StatPearls [Internet]. Treasure Island (Fla): StatPearls Publishing; 2022 Jan.