Parosteal osteoma arising in an iliac bone graft used for mandibular reconstruction

An osteoma is a benign, slowly growing, osteogenic neoplasm that can present at single or multiple sites. The multicentric form is rare and can be a part of Gardner syndrome, a hereditary dominant autosomic disease also characterized by multiple skin and subcutaneous neoplasms and intestinal polyposis. Osteomas are classified by histologic features and growth patterns. Thus, osteomas can be compact, cancellous, and mixed with regard to the first classification. Moreover, osteomas can present as periosteal when they arise peripherally from the periosteum, central when they arise from the endosteum, or extraskeletal when they are found in the soft tissue without an obvious relationship with the bone. The etiology and pathogenesis are poorly defined, and trauma and infection have been cited as promoting factors. The typical clinical presentation is that of an indolent, slowly growing, asymptomatic mass in relation to a bone, often in the craniofacial area. Osteomas are seldom found in the long or short diaphyseal bones, and their occurrence in flat bones is episodic. In detail, the most frequent localization in craniofacial bones is in the paranasal sinuses; the mandible is rarely affected, and the more typical subsites are the angle or the inferior border of the body. Only 3 cases have been reported of osteomas pertaining to the iliac bone. We could not find any case of osteomas arising from an iliac bone graft used for mandibular reconstruction. The usual treatment is surgical and indicated only when the lesion is symptomatic. Recurrence is rare, and malignant transformation has never been reported.