Malignant mixed Müllerian tumor of the ovary is a rare and very aggressive neoplasm presenting most commonly in postmenopausal women and is composed of adenocarcinomatous and sarcomatous elements and, depending on the types of these elements, can be classified as homologous or heterologous. It often has a poor prognosis.

A malignant tumor arising from epithelial cells. Carcinomas that arise from glandular epithelium are called adenocarcinomas, those that arise from squamous epithelium are called squamous cell carcinomas, and those that arise from transitional epithelium are called transitional cell carcinomas (NCI Thesaurus).