A 55-year-old woman with muscle pain and eosinophilia.

We present the case of a 55-year-old female with three months of severe, diffuse muscle aching and pain. She had recently undergone orthopedic surgery, but had otherwise not noticed any changes to her baseline health. Herphysical examination demonstrated only diffuse muscle tenderness and post-surgical changes to her right knee. Her laboratory evaluation was notable for plasma eosinophilia. An extensive rheumatological workup revealed no evidence of an underlying connective tissue disease. After undergoing a diagnostic procedure, the patient enjoyed a dramatic response to therapy for this disease. This disorder often has subtle clinical manifestations and is associated with vague systoms that can confound an accurate diagnosis.