[Acute reversible degenerative myopathy complicating Lyme disease: description of a case].

Lyme's disease is a commonly found disorder whose etiological agent is a spirochete named Borrelia burgdorferi. Its clinical presentation is usually well known, and three stages are described. However it may present symptoms which may resemble many infectious or autoimmune diseases as well. The aim of the present study is to describe a case of first stage Lyme's disease whose main clinical picture is muscoloskeletal involvement, which may mimic dermatomyositis. Many subtle characteristics (age of onset, atypical cutaneous rash) together with the involvement of muscular masses other than scapular or pelvic ones, and the bio-humoral positivity for anti-Borrelia antibodies allowed correct diagnosis to be made. We emphasize that instrumental and invasive examinations, such as electromyography and muscular biopsy, were not diagnostic in such cases.