Carcinosarcoma of the uterus: Immunohistochemical and genetic analysis of clonality of one case

Background. Carcinosarcomas of the uterus are characterized by admixtures of malignant epithelial and stromal cells, and their histogenesis remains controversial. Case. An operated case of carcinosarcoma of the uterus in a 49-year-old woman is reported with clonal analysis. The tumor was composed of carcinomatous, sarcomatous, and transitional elements in the frontal wall of the uterine body and therefore was diagnosed as a carcinosarcoma. On immunohistochemical analysis, the sarcomatous component proved negative for epithelial membrane antigen and keratin while both components were positive for vimentin. Analysis of X-chromosome inactivation showed the same pattern throughout and additionally, the same K-ras and p53 mutations were homogeneously detected. Microsatellite instability analysis showed loss of heterozygosity at D5S346 in the sarcomatous but not the carcinomatous component. Conclusions. This tumor appears monoclonal in line with the combination tumor theory, with late divergence in genetic alteration in the sarcomatous elements. (C) 2001 Academic Press.