Maxillary Ameloblastic Carcinoma in a Shih Tzu Dog

A 10-year-old castrated male Shih Tzu dog was submitted to a local animal hospital with a mass from gingiva to maxillofacial skeleton. Computed tomography revealed that strong invasion of the mass result in osteolysis in orbit and frontal bone. The excised mass was presented to the Pathology Department of the Veterinary Medicine, Jeju National University. Surgically excised mass was rubbery to firm in consistency. Histologically, the neoplastic mass was composed of irregular or interdigitating cords, islands or pseudo-glandular structures of stratified epithelial cells. These cords or islands showed typical palisading pattern of neoplastic epithelial cells to periphery without intercellular bridge (desmosome) and surrounded by eosinophilic immature collagenous matrix. Some area showed islands of well differentiated keratinizing squamous cell foci. Some lumen of glandular structures contained fibrin-like materials and RBC. These neoplastic cells showed marked invasive tendency to adjacent connective tissues and bony tissues, therefore solitary neoplastic cells were widely distributed throughout the surround connective tissue. The neoplastic cells showed positive reactions for pan-CK and CK14, weakly positive reaction for CK5/6. And the surrounding immature collagenous matrix was only labeled for vimentin.