Primary Seminal Vesicle Carcinoma. The Usefulness of Pax8 Immunohistochemical Expression for the Differential Diagnosis

Primary seminal vesicle carcinoma is a rare entity whose diagnosis can be achieved ruling out the main carcinomas that commonly invade the seminal vesicles. Although a panel of immunohistochemical markers (CA125, CK7, CK20, PSA and PSAP) has been proposed as unique for primary seminal vesicle carcinoma, a reliable positive marker is lacking. In this article, we report a case of primary seminal vesicle carcinoma in a 57-years-old man. The tumor was localized to the left seminal vesicle and histologically characterized by papillae lined by broad eosinophilic cells with pleomorphic nuclei. The neoplastic cells expressed CA125 and CK7 whereas CK20, PSA and PSAP were negative. A strong and diffuse nuclear labeling for PAX8 was detected. Since carcinomas of colon, bladder and prostate, the main differential diagnosis in this setting, have been reported consistently PAX8 negative, this marker may be very useful for a prompt diagnosis of seminal vesicle carcinoma.