A 21-year-old college student presented with a 1 month's history of "wavy red bumps" underneath her skin. She had been seen by 2 other clinics before coming to our clinic. She had not responded to previous therapy with a topical antifungal agent and a course of cephalexin. The rash was mildly pruritic but not painful. Examination revealed many serpiginous vesicles and bullae on an erythematous base involving the right medial ankle (Figure 1), as well as the plantar and dorsal right foot, which had a large tattoo (Figure 2). She had no significant medical or family history.
Quiz Answer
Cutaneous larva migrans—The patient had recently traveled to Belize and spent a considerable amount of time swimming and walking barefoot on the beach over several different days. The diagnosis was made based on this travel history and the clinical examination. Cutaneous biopsy is generally not required to diagnose cutaneous larva migrans.
Cutaneous larva migrans is a self-limiting, serpiginous eruption caused by the penetration of animal (usually domestic dogs or cats) hookworms into the epidermis, after contact with soil contaminated with animal feces. The most common nematodes associated with this condition are Ancylostoma caninum and Ancylostoma brasiliense. In general, the larvae stay confined to the epidermis, because they do not produce collagenase, which is essential for penetration of the epidermal basement membrane. They tend to migrate 1 to 2 cm/day and most often affect the lower extremities, hands, and buttocks. Although cutaneous larva migrans is found worldwide, it is most prevalent in warm, moist, tropical climates.
Oral antiparasitic agents, such as thiabendazole, albendazole, or ivermectin, can be used to treat cutaneous larva migrans.1 Cryotherapy (freezing an arc around the leading edge) and topical thiabendazole have also been used successfully.2 The patient was treated at our clinic with thiabendazole, 1.5 g/day, in 3 divided doses for 2 days. A follow-up 1 week later revealed no areas of activity, complete resolution of the bullae and erythema, and residual collarettes of scale and mild crusting.
Allergic contact dermatitis may be difficult to distinguish from cutaneous larva migrans in certain cases. Allergic contact dermatitis represents a delayed-type hypersensitivity reaction to a chemical to which the patient had previously been sensitized. Like cutaneous larva migrans, lesions may exhibit a linear configuration, which could suggest an exogenous cause of the rash. Moreover, acute cases can have vesicles and bullae, as seen in our patient, but in such cases they tend to be localized to the area of contact and do not migrate within the epidermis. Travel history can provide helpful clues, as can exposure history in cases such as poison ivy exposure during hiking.
Granulomatous tattoo reaction is a consideration in this patient, given the large tattoo on the dorsal foot. Such a reaction occurs most often in association with red pigment (cinnabar); however, the resulting erythematous nodules and plaques generally remain confined to the lines of the tattoo.1 Of note, our patient has a henna tattoo, which is unlikely to cause a granulomatous reaction, although allergic contact dermatitis reactions confined to the henna tattoo lines have been reported and are thought to be secondary to additives such as paraphenylenediamine.3
Impetigo is usually caused by staphylococcal or streptococcal bacteria. The condition often starts as an erythematous macule, which quickly becomes a small vesicle or pustule, and can be followed by rapid spread to involve surrounding skin. It is nonpruritic, and the end result is small, superficial erosions with an overlying honey-colored crust. Most often seen in children, impetigo usually occurs at sites of minor trauma.
References
- Bolognia JL, Jorizzo JL, Rapini RP, eds. Dermatology. London: Mosby; 2003:1307-1309, chapter 83.
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Albanese G, Venturi C, Galbiati G. Treatment of larva migrans cutanea (creeping eruption): a comparison between albendazole and traditional therapy. Int J Dermatol. 2001;40:67-71.
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Kang IJ, Lee MH. Quantification of para-phenylenediamine and heavy metals in henna dye. Contact Dermatitis. 2006;55:26-29.
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