A 56-year-old White man with a history of diverticulitis presented with a pruritic eruption of 1-week duration. The cutaneous eruption began 1 week after a Florida vacation spent on the beach. The eruption started out localized to the feet, then migrated to involve the thighs and eventually the trunk (Figures 1 and 2). Lesions evolved from urticarial to purpuric. The eruption caused severe pruritus, preventing the patient from sleeping. His wife reported no similar eruption; however, she did not have the same beach exposure as the patient.
Two 4-mm punch biopsies were obtained and demonstrated a normal epidermis with a moderately dense superficial and deep perivascular and interstitial infiltrate of neutrophils, eosinophils, and frequent extravasated erythrocytes within the dermis. Some endothelial cell swelling was noted, but no evidence of fibrinoid vessel wall alterations were seen. Periodic acid-Schiff stains were negative for fungal elements.
The eruption resolved within 24 hours after a single dose of oral ivermectin (200 µg/kg). No residual pigmentary alterations were observed. No recurrence was reported in the subsequent follow-up visit.
Discussion
Cutanea larva migrans (CLM) is a parasitic skin infection most frequently caused by the larvae of dog or cat hookworms, Ancylostoma braziliense or Ancylostoma caninum.1,2 The causative parasites are distributed worldwide, especially in warmer climates such as the southeastern parts of the United States.3 Larvae of the parasites are primarily found on sandy beaches. Travelers, swimmers, and children are the most prone to infection.
Humans may become infected as accidental intermediate hosts. The larvae cannot mature in humans and instead remain within the epidermis due to the lack of collagenase, a necessary enzyme to penetrate the basement membrane. However, the larvae elicit an inflammatory reaction along the migration pathway, which causes the clinical symptomatology.4
CLM most commonly presents on the lower extremities due to the site of the larval penetration. Buttocks, anogenital region, trunk, and upper extremities may also be involved. Upon the larval entrance, pruritic, erythematous, inflammatory papules develop, which may go unnoticed by many patients. Within days, exceedingly pruritic, serpiginous, reddish-brown tracks manifest as the larvae migrate at a speed of a few millimeters to centimeters a day. The size and length of the tracks can vary from a few millimeters in width and up to 1 cm to 2 cm in length.5 The larvae may be a few centimeters ahead of the tracks.
Characteristic serpiginous eruptions usually manifest within a week of exposure, but delayed onset of a few months has also been reported.6,7 Various morphologies have been documented, such as vesiculated, crusted, and bullous lesions. Secondary infection is a well-documented complication.8 Associated intense pruritus is a common reason for patients to seek dermatologic care.9 The eruption is self-limited and eventually resolves even without therapy, although it may take up to 8 weeks. Recurrence is a possibility.
Diagnosis and Treatment
Diagnosis of CLM is largely based on clinical findings and patient history. Laboratory studies may reveal nonspecific findings, and eosinophilia is rare. Skin biopsy is used to aid in the diagnosis but will not provide definitive confirmation if the larvae are not captured within the biopsy specimen. Histopathology may reveal a diffuse spongiotic dermatitis with intraepidermal vesicles containing eosinophils. In addition, there is a mixed inflammatory infiltrate composed of superficial dermal neutrophils, lymphocytes, plasma cells, and usually abundant eosinophils.
The goal of treatment is to reduce the symptoms and prevent secondary infection. The mainstay of therapy is antihelminthic agents, such as ivermectin or albendazole. Ivermectin is the preferred treatment option; ivermectin 200 µg/kg once daily for 1 to 2 days results in response rates of more than 95%.10 Albendazole is an acceptable alternative. Additionally, antihistamines are helpful in the management of pruritus. Topical corticosteroids may also be used for symptomatic relief.
Conclusion
Our case demonstrates a patient with a typical history of traveling to an endemic area with an atypical purpuric presentation. To our knowledge, this is the first case of purpuric CLM reported to date. Our case highlights the importance to include CLM in the serpiginous lesion differential. n
Dr Zheng is a dermatology resident at St. Joseph Mercy Ann Arbor Hospital in Ann Arbor, MI. Dr Henderson is a dermatology resident at St. Joseph Mercy Ann Arbor Hospital. Dr Richardson is a dermatologist at St. Joseph Mercy Ann Arbor Hospital.
Disclosure: The authors report no relevant financial relationships.
References
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