Origin of adenomatoid tumor: a comparison between the structure of adenomatoid tumor and epididymal duct cells.

In this study the structure of the adenomatoid tumor was compared with that of the epididymal duct cells. Several similar histochemical and ultrastructural features such as PAS-positive cytoplasmic granules, microvilli, intracellular vacuoles, and extracellular canaliculi were found. Based on these findings, it is suggested that the adenomatoid tumor is derived from the coelomic epithelium after it has begun to differentiate in the direction of genital epithelia. Because mesothelial cells are also derived from coelomic epithelial cells, the similarities between adenomatoid tumor and mesothelial cells may also be explained.