Carcinosarcoma of the uterus. Cytologic and ultrastructural features

A 56-year-old woman presented with a carcinosarcoma consisting of a small focus of adenocarcinoma and a larger endometrial stromal sarcoma component. Although a preoperative endometrial biopsy revealed only adenocarcinoma, an endometrial smear obtained with an endometrial brush sampler revealed many undifferentiated malignant cells and a smaller number of adenocarcinoma cells. These undifferentiated malignant cells were cytologically identical to the stromal sarcoma cells in an imprint smear from the surgically removed tumor. The cellular and ultrastructural features of the stromal sarcoma are described in detail.