We report heterotopic chondro-ossification occurring in the hand of a young man in the absence of trauma. The differential diagnosis includes: bizarre periosteal osteochondromatous proliferations of the hands and feet, mature lesions of myositis ossificans, osteogenic sarcoma, confluent lesions of extra-articular synovial chondromatosis, and nodular forms of florid periostitis. True heterotopic bone formation is a benign condition, which of itself requires no specific treatment.
