Predictors of outcome in malignant mixed müllerian tumors of the uterus

Malignant mixed müllerian tumors (MMMTs) are uncommon but aggressive gynecologic malignancies that may arise in the vagina, uterine cervix, uterine corpus, ovary or fallopian tube. Of these sites, the uterine corpus is most commonly affected.1 MMMTs are defined by the presence of an intimate admixture of carcinoma and sarcoma.The carcinomatous component may be endometrioid, serous, clear cell, or any combination of these.2-5 The sarcomatous component is, by convention, designated either homologous (resembling a sarcoma primary in the uterus) or heterologous (resembling a sarcoma usually arising extrinsic to the uterus) (Figure 15.1). Of the heterologous elements that have been described, rhabdomyosarcoma is most commonly observed, followed by chondrosarcoma and fibrosarcoma.2-6 It is not unusual to see a mixture of heterologous elements. In the majority of MMMTs, both tumor components are usually high-grade.4-6 To reflect the biphasic nature of MMMT, the current World Health Organization (WHO) classification now designates uterine MMMTs as ‘mixed epithelial and mesenchymal tumors’.7 The rarity of the disease and confusing nomenclature have resulted in limited understanding. MMMTs have historically been grouped with all other uterine sarcomas for clinical trials. In addition, much of the early work, and a few of the later studies, focused on the sarcomatous component with regard to prognosis. Early reports attempted to correlate heterologous versus homologous elements with prognosis and found a survival advantage with homologous sarcoma.8,9 A preponderance of later studies found no such differences in survival.4,6,10-14 With that said, it is the epithelial component, müllerian in origin, that appears to have the greatest influence on survival.Typically, recurrences of MMMTs are composed of carcinoma of endometrioid or papillary serous subtype.However, recurrences and distant metastases composed of sarcoma or mixed carcinoma and sarcoma also occur.