European erythema migrans disease and related disorders

European erythema migrans disease, lymphocytoma, and acrodermatitis chronica are a group of disorders associated with the bite of ixodid ticks. These disorders are now thought to be due to a single, or closely related, ixodid tick spirochetes. European erythema migrans disease closely resembles Lyme disease. Serological evaluation may help to separate spirochetal lymphocytoma from other pseudolymphomas of nonspirochetal origin and from lymphoma. Acrodermatitis chronica atrophicans, so far observed mainly in Europe, is presumably a late manifestation of this group of spirochetal disorders.