[Adenomatoid tumor of the uterus--a light-microscopical, electronmicroscopical, histochemical and immunohistochemical study].

A 34-year-old woman with an adenomatoid tumor of the uterus is reported. Light-microscopic examination showed the tumor to be cystic with a canalicular pattern. The ultrastructural findings were numerous microvilli, various intercellular spaces, desmosomes, and rich 10-nm microfilaments like tonofilament. Histochemically, the tumor cells secreted hyaluronic acids. Keratin was demonstrated diffusely in the cytoplasms of tumor cells by PAP staining. From these findings, we concluded that the histogenesis of the adenomatoid tumor was of mesothelial origin.