A 14-year-old female Mongrel dog presented with multiple, cherry-sized, well-circumscribed papillary masses on the right upper hard palate and gingival area. Histologically, the masses contained biphasic components composed of hyperplastic squamous epithelium forming papillary fronds, and underlying tortuous dilated ducts and cysts. Immunohistochemistry demonstrated that both squamous and ducts epithelium were pan-Cytokeratin (pCK) positive, but they were negative of Alpha smooth muscle (α-SMA), Vimentin and Protein 53 (P53). Duct epithelial cells were strong positive of Cytokeratin 8&18 (CK8&18), Ki-67, and weakly positive of S-100, whereas squamous component were strong positive of Cytokeratin 5&6 (CK5&6). Sialadenoma papilliferum (SP) was diagnosed based on clinical sign, gross and histopathological findings, and biochemistry.

Key words: Canine, Histodiagnosis, Salivary gland tumor, Sialadenoma papilliferum