We report the immunohistochemical features of vasitis nodosa and discuss the differential diagnosis. The patient was a 42-year-old Japanese man with bilateral small indurations of the vas deferens at the site of a previous vasectomy. Microscopically, small-sized ducts proliferated within the muscular wall of the vas deferens, and focally in the surrounding connective tissue. Immunohistochemically, most proliferating glandular cells were strongly positive for cytokeratins 7, 19, and 34βE12, and vimentin. Epithelial membrane antigen and Leu-M1 reacted against the luminal surface of the cells. Focally, glandular cells were also positive for CA125. Cytokeratin 20, carcinoembryonic antigen, and prostate-specific antigen were negative. We discuss the immunohistochemical differentiation of vasitis nodosa from prostatic adenocarcinoma, adenocarcinoma of the rete testis, and adenomatoid tumor.