A progressively enlarging soft tissue mass in a 51-year-old man

Intramuscular lipoma of the supraspinatus causing impingement syndrome

Impingement syndrome is a common ailment of the shoulder, particularly in individuals who perform repetitive overhead activities, such as athletes and laborers. Patients typically report progressive shoulder pain often exacerbated by flexion and abduction and may demonstrate a classic painful arc of motion. This article describes a case of a 45-year-old man with signs and symptoms consistent with impingement syndrome. Workup revealed a well-circumscribed, homogeneous lesion within the supraspinatus muscle on magnetic resonance imaging. The patient underwent uncomplicated marginal excision of the mass with a final diagnosis of benign lipoma. Lipomas represent one of the most common soft tissue tumors, although there are no reports of an intramuscular supraspinatous lipoma causing impingement syndrome. In our case, there were no findings on history, physical examination, or radiographs that would place neoplasm high on a differential. Magnetic resonance imaging provided the crucial information necessary to narrow the differential diagnosis and formulate a preoperative plan. Marginal resection of the mass was curative in this patient, as he remained pain free and regained excellent motion postoperatively.