Histopathological and immunophenotypical analysis of canine mucinous rectal adenocarcinoma

ABSTRACT

Rectal adenocarcinomas are uncommon in dogs and usually present poor prognosis. The present work describes the morphological and immunophenotypical findings of a rectal mucinous adenocarcinoma in a bitch. Histological analysis revealed a malignant epithelial proliferation in a tubulopapillary pattern forming multiple intratubular cell layers. Moderate amount of PAS-positive amorphous eosinophilic content within neoplastic tubules and extruded into the stroma was observed. Immunohistochemical analysis revealed neoplastic cells considered positive for cytokeratin, Her-2, COX-2 and E-caderin and with low p53 expression. A high proliferation index was observed. Based on histological and immunophenotypical findings, the diagnosis of mucinous adenocarcinoma was established.