A case of mature cystic teratoma with intestinal structures harboring intestinal-type low-grade mucinous neoplasm

The formation of gastrointestinal-type epithelium is found in 7–13% of mature cystic teratomas, which are the most common germ cell tumors of the ovary. Few cases harboring organized gastrointestinal tract formation have been reported, and a mucinous neoplasm arising in them is further rare. Here, we report a case of an ovarian mature cystic teratoma with intestinal structures harboring intestinal-type mucinous neoplasm, mimicking low-grade appendiceal mucinous cystadenoma. A 66-year-old female, with remarkably increased serum carcinoembryonic antigen (CEA) level, underwent total abdominal hysterectomy and bilateral salpingo-oophorectomy due to the ovarian tumor. The immunoprofile of the tumor showed CK7−/CK20+. We review the past literatures, and then consider that the existence of mucinous neoplasm should be kept in mind if we find elevated level of serum CEA and the organized gastrointestinal development in an ovary. The immunoprofile of CK7/CK20 is useful to determine the origin of mucinous tumors associated with mature cystic teratomas.