Hybrid Ameloblastoma of the Maxilla: A Puzzling Pathology

Abstract

Ameloblastomas are slow growing, locally invasive, benign odontogenic tumors of an epithelial origin, accounting for approximately 1% of all oral tumors. A 40-year-old man presented with a chief complaint of a swelling over the left side of his face of 4 years' duration. On examination, gross facial asymmetry was detected, and a well-defined swelling was noted intraorally involving the left maxilla medially from the mid palatal raphe and obliterating the buccal vestibule laterally. The swelling was non-tender and exhibited dual consistencies: firm in the palate and cystic in the vestibular region. Computed tomography revealed a multilocular radiolucency, which involved the left maxilla, encroached into the left maxillary sinus and the nasal complex, and caused bony erosion. Early diagnosis and treatment are the key tools in managing ameloblastomas, failure of which may lead to a significant deterioration of the prognosis and an increased recurrence rate. Uncommon variants of ameloblastomas have been gaining interest recently. To date, 25 cases of hybrid ameloblastomas have been documented in the scientific literature. We present an extremely rare hybrid type of the ameloblastoma with combined follicular, cystic, acanthomatous, and desmoplastic variants, which render it the first of its kind to have ever been reported.

Keywords: Ameloblastoma; Maxillary neoplasms; Maxillary sinus; Odontogenic tumors.

Figure 1

A) Extraoral swelling involves the left cheek. B) Intraoral swelling is seen in the left maxilla.

Figure 2

A) Multilocular Radiolucency Involves The Left Maxilla And The Adjoining Sinus, Exhibiting A Soap-Bubble Pattern. B) Axial Computed Tomography Image Shows A Multilocular Expansile Lesion Encroaching Into The Sinuses And The Nasal Cavity.

Figure 3

A) Excised tumor along with the involved teeth is depicted here. B) Placement of the obturator to close the surgical defect is illustrated here.

Figure 4

A) H & E 20x section shows follicles (black arrow) and peripheral hyperchromatic palisading ameloblast-like cells (green arrow) with stellate reticulum-like cells (red arrow) in the center intervening with a dense hyalinized desmoplasia connective tissue (yellow arrow). B) H & E 20x section presents follicles with peripheral hyperchromatic palisading-like cells (black arrow) with squamous metaplasia (blue arrow) and a few cells undergoing cystic degeneration (red arrow) with dense hyalinized desmoplasia (green arrow) like connective tissue stroma. C) H & E 20x section depicts stromal desmoplasia.