We experinced a rare case of osteochondromatosis in the subacromial bursa. The patient was a 65-year-old man who complained of left shoulder pain, touchable mass lesion and slightly limited of range of shoulder motion. Roentgenograms and arthrography showed several calcified or ossified mass lesions in the extraarticular region. He was treated with a surgical procedure that consisted of anterior acromioplasty, removal of the mass lesion and resection of the subacromial bursa. Histologic examination showed this case might be a different etiology from the typical synovial osteochondromatosis.
