Synchronous colonic adenocarcinoma and well-differentiated neuroendocrine tumor arising in a mature cystic teratoma of ovary - rare presentation in a postmenopausal woman with literature review.

Mature cystic teratoma of the ovary (MCT) is rare in pre and postmenopausal age patients. Among various types of malignant transformation in MCT, adenocarcinoma is a rare subtype. Dual type tumors arising from ovarian MCT have been described in the literature very rarely. A 47-year-old postmenopausal female patient presented with abdominal mass for ten years. The radiological opinion was a dermoid cyst. Grossly, a 22 × 20 × 10 cm, unilocular cystic left ovarian mass with intact capsular surface and focal thickened wall measured 3.0 cm. Microscopically, it showed components of all three germ cell layers. In addition, features of colonic type adenocarcinoma and well-differentiated neuroendocrine tumor (carcinoid) were noted and confirmed by immunohistochemistry (IHC). We report this rare case of synchronous malignancy arising from an ovarian MCT with a clinicopathological review.