Non-traumatic myositis ossificans circumscripta at elbow joint in a 9-year old child

Abstract

Myositis ossificans circumscripta (MOC) is a kind of self-localized, benign and tumor-like lesions often seen in adults, with approximately 75% of cases caused by trauma. We reported a case of non-traumatic MOC occurred at the elbow joint in a 9-year old child and it has been excised by surgery. After 18 months follow-up, a favorable outcome has been achieved with the Broberg-Morrey score of 100. We suggest that surgical resection should be done as soon as the diagnosis is confirmed.

Fig. 1

The anterior-posterior and lateral radiographs of the right elbow joint showing distal ossification myositis of the right upper arm.

Fig. 2

A round mass sized about 5.53 cm × 4.10 cm × 5.87 cm was seen in front of the distal humerus. MRI scan showed multiple cystic lesions and mild bone marrow edema in the distal humerus and ulna olecranon.

Fig. 3

Histopathologic result showed that the mass center was filled with immature fibrous tissue and bone tissue and scattered by lots of chronic inflammatory cells, and the peripheral area was filled with differentiated mature trabecular bone tissue.