Histologic demonstration of intradermal spirochetes in a patient with Lyme disease.

Spirochetal organisms were demonstrated histologically in skin biopsy specimens from a patient with Lyme disease and erythema chronicum migrans. The patient responded rapidly to penicillin G benzathine administration. Convalescent serum contained a high titer of antibody to an lxodes dammini spirochete antigen. The finding of spirochetes in an erythema chronicum migrans lesion in a patient with clinical Lyme disease supports further recent evidence that this illness is an infectious disease caused by a tick-borne bacterium. The skin biopsy may be a useful diagnostic tool in this disease.