Extraarticular pigmented villonodular synovitis of the shoulder: a case report.

A rotator cuff tear was diagnosed in a 57-year-old woman based on physical examination and magnetic resonance imaging studies. At operation, an abnormal bursal lesion also was found. The lesion was completely extraarticular and was identified histologically as pigmented villonodular synovitis. The patient was treated with complete bursectomy and repair of the rotator cuff tear and remains asymptomatic 21 months after operation. Pigmented villonodular synovitis is a condition characterized by cell proliferation and deposition of hemosiderin into the lining tissues of joints, tendons, and bursae. The extraarticular form of pigmented villonodular synovitis is extremely rare and usually represents an extension of a primary intraarticular process. Only a few cases have been reported in which the lesion was found exclusively outside the joint with no intraarticular segment. In reviewing the literature, no case of exclusively extraarticular pigmented villonodular synovitis of the shoulder was found. The sequelae of extraarticular pigmented villonodular synovitis are poorly understood, but this lesion can be locally invasive, and if left untreated, may destroy surrounding tissues. Therefore, early diagnosis and treatment are important for optimal results.