Mucinous carcinoid tumor of the appendix presenting as bilateral ovarian tumors.

Mucinous carcinoid tumor of the vermiform appendix, an uncommon variant of appendiceal carcinoid, may present clinically with ovarian metastases. We studied a tumor by immunohistochemistry and electron microscopy and reviewed eight similar cases from the literature. The primary and metastatic tumors in our case were composed of mucin-producing cells and small argyrophilic cells arranged in cords and acini. Tumor cells in both primary and metastatic sites exhibited identical patterns of immunoreactivity for epithelial antigens (epithelial membrane antigen, carcinoembryonic antigen) and neuroendocrine antigens (serotonin, vasoactive intestinal polypeptide, adrenocorticotropic hormone). Ultrastructurally, the cells contained either mucin vacuoles or dense-core neurosecretory granules; rare individual cells contained both types of inclusions. When bilateral solid mucinous ovarian tumors are discovered at laparotomy, diagnostic appendectomy is indicated if no obvious extraovarian primary tumor can be found.