Keratinizing ameloblastoma in a 9-month-old llama (Lama glama).

Abstract

A 9-month-old male llama (Lama glama) was presented because of a rapidly growing mass on the right side of the face. Radiographs revealed a marked expansion of the right caudal face region with bone lysis involving the maxilla and the nasal, lacrimal, zygomatic, and palatine bones. Cytologically, the mass consisted of atypical round to polygonal cells with round nuclei and basophilic cytoplasms that formed acini and rows. Histologically, the mass consisted of anastomosing cords and sheets of neoplastic odontogenic epithelial cells embedded in a loose fibrovascular connective tissue. Single layers of peripheral, polarized, palisading, columnar epithelial cells were seen at the edges of some cords. Within the centers of the cords, epithelial cells showed rapid progression to keratin production. The histologic diagnosis was keratinizing ameloblastoma. Ameloblastomas are neoplasms of odontogenic epithelium that tend to be locally aggressive and can cause substantial destruction of bony structures. Because ameloblastomas do not tend to metastasize, they can be successfully treated by complete surgical excision, performed before extensive bony destruction occurs. Ameloblastoma, although expected to be rare, should be onthe list of differential diagnoses for facial swelling in llamas.