Malignant mixed müllerian tumor of the extraovarian secondary müllerian system. Report of two cases and review of the English literature.

OBJECTIVE To report two cases of malignant mixed müllerian tumor of the extraovarian secondary müllerian system and to identify cases reported in the English literature. DESIGN Two cases are described and discussed along with cases reported previously in the English literature. SETTING The University of Cincinnati Medical Center. PATIENTS (1) A 62-year-old woman with a bilateral ovarian poorly differentiated endometrioid adenocarcinoma with multiple peritoneal metastasis and a malignant mixed müllerian tumor with heterologous elements arising from the pelvic peritoneum. (2) An 83-year-old woman with a malignant mixed müllerian tumor with heterologous elements arising from the cecal peritoneum. RESULTS Seventeen previously reported cases were identified in the English literature. CONCLUSIONS The malignant mixed müllerian tumor of the extraovarian secondary müllerian system is a rare disease with only 17 cases reported to date to our knowledge. The prognosis is poor. Of 12 patients with follow-up information available, 10 died within 1 year and 2 within 2 years after diagnosis. The histogenesis of the tumor remains unclear; however, data exist that support transformation of epithelial neoplastic cells into sarcomatous cells (metaplastic theory) and origin from a single totipotential cell. It is possible that both situations may occur.