Odontoameloblastoma: report of a case with 17 year follow-up

Abstract

The odontoameloblastoma is an exceedingly rare mixed epithelial and ectomesenchymal odontogenic neoplasm combining the histomorphologic features of ameloblastoma with those of odontoma. Most cases arise within the first three decades of life in the posterior jaws, equally divided between the maxilla and mandible. It presents as a unilocular or multilocular lucent lesion with a variable degree of internal radiopacity and commonly displaces teeth. It is an unencapsulated, locally aggressive neoplasm that infiltrates the adjacent host bone. It should be treated in the same manner as conventional ameloblastoma. Earlier literature refers to this lesion as “ameloblastic odontoma.” The number of acceptable cases is less than twenty, as many of the reports as fail to present convincing evidence to substantiate the diagnosis and likely represent ameloblastic fibro- odontomas or developing or mature odontomas. We report a case that arose in the right posterior maxilla of a 17 year old female, filling the right maxillary sinus with a 4.2 x 3.9 x 3.8 cm mixed lucent-opaque lesion that expanded the medial and lateral sinus walls, impinged on the orbital floor, eroded the anterior sinus wall and expanded the posterior alveolar ridge and palate. The patient received a local excision and was free from recurrence after a post-operative follow-up period of 17 years. Histologically, the lesion exhibited areas of typical ameloblastoma, but with focal dental hard tissue formation, transitioning into areas of complex odontoma. The odontoameloblastoma should not be considered a “collision tumor” as the mesenchymal, hard tissue component, consisting of enamel and dentin, is intimately admixed with the ameloblastomatous epithelial component.