Primary mullerian carcinosarcoma of the retroperitoneum: Report of a case

A mullerian carcinosarcoma or malignant mesodermal mixed tumor (MMMT) origi nated from the retroperitoneum of a 51-year-old woman; only two previous si milar cases have been reported. The 1,040 gm tumor was found in the left re troperitoneal space; the center of the tumor was extensively liquified. The uterus, fallopian tubes, and ovaries were unremarkable. The histopathologi cal features of the tumor were typical of MMMT, homologous type. The adenoc arcinomatous component of the tumor was immunohistochemically positive for cytokeratin 7 and negative for cytokeratin 20. MMMTs arising in extragenita l sites are rare, and most of them arise from the peritoneum. The histogene sis of extragenital MMMTs remains speculative, but the origin from the "sec ondary mullerian system" is most likely.