Bone Scan in Identification, Assessment of Initial Extent and Response to Therapy in Polymyositis

This is a 51-year-old male who presented with abdominal pain, bilateral proximal upper and lower extremities pain and weakness, and decreased urine output with abnormal kidney function test; Urea and creatinine levels were elevated at 231.5 mg/dl and 11.05 mg/dl, respectively. Initial bone scan showed increased uptake within several muscles suspicious for polymyositis, this was confirmed by biopsy of the right triceps, identified by bone scan as the best superficial biopsy site. Pelvis and thigh MRI demonstrated diffuse hyperintense signal on fluid sensitive sequences involving several muscles. Renal biopsy showed acute tubular injury. He was treated with steroids resulting in significant improvement. A repeat bone scan showed near complete resolution of the muscular uptake seen at presentation. This case nicely illustrates the role of bone scanning in the initial recognition and determination of the extent of polymyositis with identification of a suitable biopsy site as well as assessment of response to treatment.