Lyme myositis.

Myositis has been reported as a rare manifestation of Lyme disease, and Lyme myositis can be an important consideration in the differential diagnosis of unusual cases, especially in patients who live in or travel to endemic areas. We report the case of a 43-year-old man who presented with focal myositis of the proximal lower extremity and was subsequently diagnosed as having Lyme myositis. The patient had previously experienced a febrile illness and rash, but had no ongoing symptoms of Lyme disease. Myositis was confirmed by magnetic resonance imaging and muscle biopsy; Borrelia burgdorferi infection was confirmed by Lyme serology and polymerase chain reaction testing of synovial fluid and biopsy material. The current case is reviewed in the context of findings from previous case descriptions.