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.
Etiology Hookworm larvae of cats/dogs
(Ancylostoma braziliense, Uncinaria stenocephala, A. 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 accident hosts (humans) when they
are stepped on with bare feet, but cannot cross the basement membrane.
Thus the larvae wander serpiginously under the skin giving it 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.
Cutaneous larva migrans Serpiginous
lesion on the foot of and adolescent 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, and hands.
Visceral larvae (typically Toxocara canis, T. cati, A. lumbricoides)
can cause peripheral eosinophilia, hepatomegaly, and pneumonitis.
The differential diagnosis of cutaneous larvae migrans includes
phytophotodermatitis, tinea pedis, erythema chronicum migrans, jellyfish
sting, and granuloma annulare.
Dermatopathology PAS may show larva
in a suprabasalar burrow, spongiosis, intraepidermal vesicles, necrotic
keratinocytes, chronic inflammatory infiltrate with many eosinophils.
Cutaneous larva migrans is typically self-limited because the
human skin is an accidental “dead-end” host. Most
larvae die after 2 to 4 weeks of aimless wandering underneath the
skin, and the skin rash resolves in approximately 4 to 6 weeks.