Undifferentiated carcinoma arising in ovarian mature cystic teratoma: a case report and literature review.

Malignant transformation is a rare complication of the mature cystic teratoma of the ovary. Most of these histologic types are squamous cell carcinoma, and other types are exceptionally rare. Here, we present an extremely rare histology of malignant transformation, an undifferentiated carcinoma, arising in mature cystic teratoma of the ovary. A 48-year-old woman was referred due to abdominal distension and palpable pelvic mass. Computed tomography showed 16- and 12-cm-diameter mixed solid and cystic tumors in bilateral ovaries. Surgical exploration revealed bilateral ovarian tumors with multiple nodules on the whole peritoneum, liver capsule, and diaphragm. Cytoreductive surgery was performed, leaving <1 cm tumors. On pathologic review, the tumor was confirmed as undifferentiated with an adenosquamous carcinoma component arising in mature cystic teratoma. The patient died 7 days postoperatively due to uncontrolled malignant ascites and pleural effusion. We report a case of undifferentiated carcinoma arising from mature cystic teratoma, and we review the clinicopathologic features of this rare case.