Carcinosarcoma (malignant mixed müllerian tumor) of the uterus with a rhabdoid tumor component. An immunohistochemical, ultrastructural, and immunoelectron microscopic case study.

A case of uterine carcinosarcoma (malignant mixed müllerian tumor) of the uterus containing a rhabdoid tumor element is described. In addition to a malignant glandular component and anaplastic sarcomatous areas, this tumor had multiple foci with histologic and ultrastructural features of malignant rhabdoid tumor. Vimentin positivity by immunohistochemistry was confirmed by immunoelectron microscopy. Although three malignant rhabdoid tumors of the uterus have been previously described, in addition to rhabdoid differentiation in an endometrial stromal sarcoma, to our knowledge this is the first report of rhabdoid tumor differentiation occurring within a uterine carcinosarcoma.