Collision of endometrioid carcinoma and stromal sarcoma of the uterus: a report of two cases.

Two uterine collision tumors are reported, one in an 85-year-old woman and the other in a 47-year-old woman. Each tumor was composed of a smaller grade 1 endometrioid adenocarcinoma that was distinct from a larger component of high-grade stromal sarcoma. The separate components in these tumors could be detected on gross, microscopic, and immunohistochemical studies. The clinicopathologic features and indolent behavior of these tumors suggest that they should be distinguished from malignant mullerian mixed tumors.