Make the Diagnosis

Make the Diagnosis - November 2016

A 45 year old healthy male presented to the office with pruritic lesions on the leg for several weeks. He described a crawling sensation under the skin and states the lesions are slowly moving. On physical examination, erythematous, winding, linear tracts were present on his left thigh.

What's your diagnosis?​

Cutaneous larva migrans

Erythema chronicum migrans


Cutaneous larva migrans

Cutaneous larva migrans (CLM) presents as a self-limited cutaneous eruption. It is also known as creeping eruption. Animal (dog and cat) hookworms such as Ancylostoma braziliense are responsible for most CLM infestations in the central and southeastern United States. The hookworms are often acquired while walking barefoot in contaminated sand. Carpenters, plumbers, and gardeners are also likely to be affected. Ova from the hookworms hatch into larvae that penetrate into skin.

On physical examination, lesions are erythematous, linear and serpiginous. Exposed sites, such as lower legs, hands, genitals, buttocks, and feet are most commonly involved. The migration begins about 4 days after onset. There is often intense pruritus and lesions advance 1-2 cm per day. Old lesions fade as the larvae migrate. They may have periods of rest, evidenced as papules. The differential diagnosis includes other parasites (uncinariasis, gnathostomiasis, strongyloidiasis, myiasis), dermatophytosis, phytophotodermatitis, erythema chronicum migrans, granuloma annulare, and bullous impetigo.

CLM is often a clinical diagnosis. Histopathology often reveals an inflammatory infiltrate or, if taken from an advancing lesion, part of the parasite. Serology may reveal an eosinophilia.

CLM is usually a limited infestation that typically resolves within 2-8 weeks, although longer timelines have been reported. Complications include cellulitis, abscess formation, and Loeffler syndrome (patchy lung infiltrate and eosinophilia). Antihistamines alone may be used to alleviate the accompanying pruritus, but curative treatment is often used. First-line curative therapies include oral albendazole and ivermectin but topical tiabendazole is also effective. Our patient responded well to oral ivermectin.

Case and photo courtesy of Mark Ash, MS; Brody School of Medicine,Greenville, North Carolina; and Donna Bilu Martin, MD; Premier Dermatology, MD, Aventura, Florida.

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