Intestinal adenocarcinoma arising in a mature cystic teratoma of the ovary: a case report.

Gastrointestinal adenocarcinoma arising in mature cystic teratomas of the ovary is extremely rare. We report a case of well-differentiated intestinal adenocarcinoma arising in a mature cystic teratoma of the ovary in a 77-year-old woman, presenting as acute abdomen with ovarian torsion. An immunohistochemical study revealed expression of CK20 and CK7, and the tumor was also positive for MUC2. The patient had no evidence of disease after 12 months of follow-up.