Primary seminal vesicle adenocarcinoma in a squirrel monkey (<i>Saimiri sciureus</i>)

This report presents the case of a 22-year-old male squirrel monkey with primary seminal vesicle adenocarcinoma (PSVA). The animal presented with hematuria and emaciation. Pathological autopsy of the seminal vesicle tumor revealed an irregularly shaped, white, solid mass showing ductal/papillary and solid patterns and periodic acid-Schiff-positive mucus in the duct. The vesicle was dilated by blood. Tumor cells showed cytoplasmic eosinophilic granules, and a transition to tumor tissue was observed. Immunohistochemical analysis indicated that all tumor cells were cytokeratin-negative; only ductal/papillary cells were vimentin-positive. Other organs were tumor free. PSVA was diagnosed based on the site of tumor origin and histopathology, similar to PSVA in laboratory rodents. This study reports a case of PSVA in a new-world monkey.