Osteochondroma of maxillofacial region: Tumor arising from two different developmental bones.

Osteochondromas are benign bony tumors which are commonly believed to originate by the proliferation of epiphyseal cartilage into the surrounding tissues. However, this hypothesis cannot explain the occurrence of this tumor in the intramembranous bones and soft tissue. Since most of the craniofacial bones have intramembranous origin, the occurrence of this lesion in this territory is considered rare. Contrary to the above hypothesis, Lichtenstein proposed that this entity arises from the metaplastic changes in the periosteum which explains the occurrence of this tumor in endochondral as well as intramembranous bones and also in soft tissues. Complying with Lichtenstein's hypothesis, the authors are presenting two cases of osteochondromas with one arising from the endochondral bone (the coronoid process of the mandible) and the other from an intramembranous bone (lateral pterygoid plate of the sphenoid).