Myositis ossificans of the chest wall in an 8-year-old boy: a case report of a diagnostic pitfall.

Myositis ossificans of the chest wall is extremely unusual with fewer than a dozen reported cases. In addition, the occurrence in children younger than 10 years is extremely rare. We report a case of an 8-year-old male who presented with painful and progressively enlarging left-sided chest wall mass. The tumor showed close histo-morphological mimicry with osteosarcoma. Moreover, the characteristic radiographic findings of myositis ossificans were absent. The age of the patient and the absence of attachment to the rib helped exclude extra-skeletal and parosteal osteosarcomas, respectively. The patient was doing well 4 months after surgery.