Adenomatoid tumor of the ovary: an immunohistochemical and ultrastructural study.

A rare case of adenomatoid tumor arising in the ovary is presented. At autopsy on a 61-year-old woman, a soft, solid and cystic tumor, measuring 0.8 X 0.7 cm, was detected in the hilus of the left ovary. Light microscopic study showed characteristic features of adenomatoid tumor. Alcian blue stain, with and without hyaluronidase pretreatment, revealed the presence of hyaluronic acid on the luminal surface and in the vacuoles of the tumor cells. Immunohistochemical stains of tumor cells were positive for low-molecular-weight cytokeratin (PKKL), vimentin, and carbohydrate antigen (CA) 125, whereas they were focally positive for high-molecular-weight cytokeratin (34 beta E12). They were negative for factor VIII-related antigen (FVIII-RAG), Ulex europaeus I lectin (UEA I), carcinoembryonic antigen (CEA) and epithelial membrane antigen (EMA). Ultrastructural studies disclosed surface microvilli and bundles of tonofilaments. These observations strongly support the idea of this tumor being of mesothelial origin.