Adenomatoid tumor of the epididymis: immunohistochemical study of 8 cases.

The immunohistochemical characteristics of 8 adenomatoid tumors of the epididymis are reported. Using the peroxidase antiperoxidase technique and the avidin-biotin complex method, antibodies against carcinoembryonic antigen, factor-VIII-related antigen and keratin were tested. In agreement with previous findings strong cytoplasmic staining for keratin was seen in all the tumors, whereas the factor-VIII-related antigen and carcinoembryonic antigen were absent. These results suggest a mesothelial origin of the adenomatoid tumor.