RESUMO
The authors report an unusual case of myositis ossificans in the temporal muscle manifesting as grave opening limitation of the mouth and a hard firm mass in the right temporal fossa. CT scan examination revealed a bone density mass located in the region of the right temporal fossa, that fussed the right temporal bone with the right coronoid process and a joint-like image in the middle portion of this mass. Traumatic myositis ossificans is a pseudotumor-like benign disease most frequently found in extremities of young population. Cases in the craniofacial skeleton are rare. The masseter and sternocleidomastoid muscles are most commonly affected in this location. The clinicopathological features of scalp myositis ossificans may mimic other soft tissue tumors, requiring care for the differential diagnosis. Histologically, osteoblastic activity is sometimes observed, similar to an osteosarcoma. Then differential diagnosis between both entities must be established.