Eleven eases of adenomatoid tumors arc described. There were 9 males and 2 female with an average age of 51 years. These tumors arose in The male and female genital tract. Five of these were located in the epididymis

two in the te- stis

two in the uterus and the last two

one in the spermatic cord and the other in the bladder.The tumor cells of the 11 cases studied were immunoreactive for keratin

but none of these for factor VIII.Only the endothelial cells of the blood vessels in the tumors were positively stained.Ultrastructural examination of 4 cases revealed long brushy microvilli on the surface of the tumor cells lining the lumina. These tumor cells with the presence of tonofilaments in the cytoplasm

were desmosomes.These results strongly support the mesothelial origin of the adenomatoid tumors