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.
CASE REPORTThe patient, a 43-year-old man from Olmsted County, Minnesota, presented to the emergency department in February 2005 with a 3-week history of left knee and thigh pain and swelling. He first noted symptoms in the posterior aspect of his left knee while sitting at rest. There was no antecedent trauma. The pain first worsened and then improved within 1 week, while the swelling continued to progressively worsen. Approximately 10 days prior to admission, the swelling and pain progressed to include his left thigh and, to a lesser extent, his left calf. The swelling became very pronounced, and his leg felt "tight." Movement of the knee caused pain in his thigh, especially the medial aspect of the thigh, which caused increased difficulty in walking. Two days prior to admission, the patient presented to an outside urgent care facility. A Doppler ultrasound was performed to rule out deep venous thrombosis. The results were negative. He was discharged with instructions to follow up with an orthopedist.On the evening prior to admission, the patient described feeling malaise and, that night, awoke with drenching sweats. He presented to his outpatient appointment the following day, where he was noted to have thigh swelling, a lesser degree of calf swelling, a knee effusion, and intense medial thigh tenderness, but no knee tenderness. A Doppler ultrasound was again performed, but the results remained negative. He was directed to our emergency department, where he was evaluated and admitted to the hospital. Information obtained upon admission revealed no history of fevers, chills, or sweats, except for the previous night. He reported no pain in the ipsilateral calf. There were no other painful or swollen joints or back pain. He had no rash, cough, dyspnea, chest pain, headache, sinus symptoms, urinary symptoms, nausea, vomiting, diarrhea, or hematochezia. His medical history was significant only for hypertension, for which he took atenolol as well as daily aspirin. There was no history of arthritis or gout.Upon examination, the patient was afebrile. He had a large left knee effusion, which was warm but not tender or erythematous. The left thigh was also swollen to a circumference 7 cm greater than that of his right thigh. The ...