Mazabraud's syndrome: intramuscular myxoma associated with fibrous dysplasia of bone

A 53 year old male with a large swelling on the medial aspect of his right thigh was referred with a presumptive diagnosis of soft tissue sarcoma. However, biopsy revealed intramuscular myxoma and X-rays and CT scans suggested fibrous dysplasia of adjacent bone. Angiography had shown an expanded, hypervascular, intramedullary lesion in the femur, and a large avascular soft tissue mass lying medially in the distal thigh. Fibrous dysplasia of the femur was confirmed on bone biopsy. Subsequently one large and two smaller intramuscular myxomata were excised, with an uneventful postoperative course. This case illustrates Mazabraud's syndrome: the rare association between benign intramuscular myxoma and fibrous dysplasia of bone.