PRIMARY AND SECONDARY ERYTHEMA MIGRANS IN CENTRAL WISCONSIN

Background and Design.-We report a series of 28 consecutive patients w ith erythema migrans (EM) who underwent skin biopsies for culture of B orrelia burgdorferi. Culture results, Lyme serologic findings, and cli nical features in patients with only primary EM are compared with thos e in patients with secondary EM. Results.-Culture preparations of skin specimens obtained from six of 12 patients with only primary EM, and from 14 of 16 patients with secondary EM were positive for B burgdorfe ri. Seven patients with only primary EM were initially seronegative, a nd only one patient had an annular lesion. A central crusted punctum w as present in five of six primary EM lesions that were not culture pos itive, but in none of nine culture-positive primary EM lesions. Patien ts with secondary EM were all seropositive and had less cutaneous and more constitutional symptoms than patients with only primary EM. Three patients with secondary EM had abnormal liver enzyme profiles, one pa tient had complete heart block, an d one patient had myocarditis simul ating infarction. Less than one third of all patients recalled a tick bite. An isomorphic nonresponse was seen in skin previously involved w ith secondary EM in one patient who had a drug exanthem from amoxicill in. Conclusions.-Borrelia burgdorferi can be reliably cultured from sk in biopsy specimens of secondary EM. Culture preparation aids definiti ve diagnosis of Lyme disease in patients with only primary EM who ofte n lack constitutional symptoms, have nondiagnostic lesions, or are ser onegative.