Recurrent ameloblastic fibro-odontoma in a 10-year-old boy

Abstract

The ameloblastic fibro-odontoma is a rare odontogenic tumor.1-7 It is composed of connective tissue characteristic of an ameloblastic fibroma and calcified tissue identifying the tumor as a complex odontoma. The earlier used term “mixed tumor” was abandoned after the first World Health Organization (WHO) classification8 because of the fundamental decision that the odontogenic tumors should be classified according to the stages of dental development and not to the structures of the tumor.9 In the revised WHO classification10 of odontogenic tumors, a distinction was drawn between the ameloblastic fibro-odontoma and the ameloblastic fibro-dentinoma, both newly accepted entities. The diagnosis of an ameloblastic fibro-odontoma is based on the histologic evidence of an ameloblastic fibroma with active odontogenic epithelium embedded in an embryonal connective tissue. The cell-rich embryonal connective tissue is free of collagen and mimicks a primitive dental pulp. The active odontogenic epithelium is organized in bands and bud-like conglomerates and consists of 2 layers of round or cuboidal cells. The calcified tissues are those of a complex odontoma; compound odontomas do not occur in this entity. In the revised WHO classification10 of odontogenic tumors, the ameloblastic fibro-odontoma was categorized into the group “odontogenic epithelia with odontogenic ectomesenchyme, with or without formation of hard tissue.” In the following case report the differential diagnosis and therapy of this rare lesion are discussed.