Cutaneous larva migrans is a skin infestation caused by nematode larvae that penetrate the skin and migrate leaving a characteristic erythematous, serpiginous burrow underneath the skin.
SYNONYM Creeping eruption.
INCIDENCE Uncommon; mostly in tropical climates (see Geography).
ETIOLOGY Hookworm larvae of cats/dogs (Ancylostoma braziliense, Uncinaria stenocephala, Ancylostoma caninum), cattle (Bunostomum phlebotomum), or other nematodes.
GEOGRAPHY Common in warm, humid, sandy, coastal areas, central United States, southern United States, central America, South America, and the Caribbean.
In animal hosts (dogs, cats), the hookworm penetrates the skin and spreads through the lymphatic and venous systems to the lungs, breaks through into the alveoli, migrates to the trachea, and is swallowed. The hookworm then matures in the intestine and produces eggs that are excreted by the animal host. Once the animal defecates infested feces, the hookworm ova in the sand or soil hatch into larvae. The larvae penetrates the skin of accidental hosts (humans) when they are stepped on with bare feet or come into contact with other bare skin, but cannot cross the basement membrane and are confined to the epidermis. Thus the larvae wander serpiginously through the epidermis creating visible track patterns, giving the nickname “creeping eruption.”
Larvae tend to penetrate the skin and begin to migrate at a rate of 1 to 2 cm/d for 4 weeks to 6 months and may cause pruritus. After aimless wandering, the larvae typically die and the cutaneous tracts self-resolve. Systemic symptoms are absent.
TYPE Tracks/burrows (Fig. 24-1). Vesicles or bullae can develop in individuals previously sensitized to the invading species.
Cutaneous larva migrans
Serpiginous lesion on the buttock of an infant infected with hookworm larvae.
COLOR Flesh colored to pink.
SIZE Width 2 to 3 mm, extending at 1 to 2 cm/d.
NUMBER One, several, or many tracks.
DISTRIBUTION Exposed sites: feet, lower legs, buttocks >> hands, thighs.
Can be associated with peripheral blood eosinophilia and generalized pruritus. Very rare cases of hematogenous dissemination and resultant pulmonary infiltrates have been reported.
The differential diagnosis of cutaneous larvae migrans includes phytophotodermatitis, tinea pedis, erythema chronicum migrans, jellyfish sting, contact dermatitis, larva currens, and granuloma annulare.
DERMATOPATHOLOGY PAS may show larva in a ...