This 26-year-old white man complained of a dull ache in the hip over a 4-months period. There was no history of trauma, unusual athletic activity, vigorous massage, or other cause of local contusion was obtained. He had experienced no fever or weight loss. Physical examination revealed a tender mass measuring approximately 5 x 5 cm anterior to the left hip. The overlying skin appeared normal. Laboratory evaluation including serum calcium, phosphate, and erythrocyte sedimentation rate was within normal limits. Plain radiographs showed a large, densely-ossified para-articular mass adjacent to the ilium