Adenoid Ameloblastoma- A very rare, odontogenic tumor variant with less than 20 reported cases in the literature: Report of two cases and literature review

Abstract

Abstract Introduction/Objective We describe two cases of Adenoid Ameloblastoma (AA), a very rare, hybrid variant, of two of the most common odontogenic neoplasms (Ameloblastoma and adenomatoid odontogenic tumors). AA is a benign epithelial odontogenic tumor characterized microscopically by epithelium resembling conventional ameloblastoma, with additional duct-like structures, epithelial whorls, and cribriform architecture. Dentinoid deposits, clusters of clear cells, and ghost-cell keratinization may also be present. These tumors do not harbor BRAF or KRAS mutations and their molecular basis appears distinct from conventional ameloblastoma but remains unknown. The lesion tends to recur, and sometimes, only correctly diagnosed after recurrence. Methods/Case Report Adenoid Ameloblastomas were identified after a review of the Temple University, Department of Pathology archive from 2012-2022. A total of four specimens (two patients) were identified. Results (if a Case Study enter NA) Case# 1 22-years-old female Biopsy Location/ size: Mandible, left, 2.1 cm. Microscopic: Neoplastic proliferation composed of odontogenic epithelium in a plexiform pattern with the formation of pseudo glandular structures of variably sized cystic spaces, the peripheral epithelial cells are palisaded with reversed polarity. The central cells have clear cytoplasm and resemble stellate reticulum with occasional tight whorls of cells noted. Hemorrhage and giant cells are present in granulation tissue. The lesion was incompletely excised. Diagnosis: Benign odontogenic tumor. Case#2 (1st occurrence): -49-years-old male -Biopsy -Location and size of lesion: Maxilla-left anterior, 0.9 cm. -Microscopic: Cyst lined by loosely arranged epithelial cells with a basal cell layer having hyperchromatic and palisaded nuclei. Knots of squamous cells are present within the cyst lining. The luminal layer is flattened to cuboidal and nonkeratinized. Duct-like openings are present within the epithelium and contain myxoid stromal tissue. Focally the epithelium extends into the connective tissue as thin anastomosing strands surround the myxoid tissue. -Diagnosis: Benign odontogenic tumor. Case#2 (2nd occurrence): -Biopsy -Diagnosis: Benign odontogenic tumor Case#2 (3rd occurrence): -Excisional biopsy -Diagnosis: AA Conclusion AA is a rare, aggressive odontogenic tumor variant with morphologic overlap with other odontogenic lesions; therefore, oral pathologists and clinicians should be familiar with this entity to achieve an accurate diagnosis and prompt management.