Pseudomalignant myositis ossificans of the wrist causing compression of the ulnar nerve and artery. A case report.

Myositis ossificans (MO) is a condition characterised by focal, benign and self-limited idiopathic heterotopic bone formation. It is extremely rare in the hand and wrist and may lead to concomitant nerve compression. Because of the rare incidence of pseudomalignant MO at the wrist and hand, we found it of interest to report a case of this condition localised to the wrist. A 31-year-old female patient presented with swelling and pain of her left wrist. The physical examination findings, magnetic resonance imaging and Tc-99m bone scan suggested acute osteomyelitis or a tumoral condition. Incisional biopsy and pathological examination was done. The microscopic findings confirmed that the lesion was pseudomalignant MO. The lesion was removed totally and decompression of the ulnar nerve and artery was achieved. The patient regained full asymptomatic range of motion of all digits and wrist and the numbness of the fourth and fifth digits had subsided at follow-up five months later.