Atypical femoral head osteonecrosis: a case report.

We report the case of a 65-year-old man presented with polymyalgia rheumatica. After a week on corticosteroid (40 mg/d), pain was relieved rapidly. Bone scan, requested to precisely localize osteoarticular lesions, showed high uptake in the external aspect of the head of left femur. In the clinical setting, bone scan and MRI appearances are suggestive of osteonecrosis, probably of recent onset. The final diagnosis of atypical necrosis of the femoral head, most probably secondary to corticoid therapy, was thus established.