Final Diagnosis -- Mixed Müllerian Tumors



Mixed Müllerian tumors (MMT) or carcinosarcomas comprise 2-3 % of all uterine malignancies occurring in older post-menopausal women. They are tumors in which both the epithelial and non-epithelial components are histologically malignant. They are further subdivided into homologous and heterologous types. The most common presenting symptom is post- menopausal uterine bleeding. Other symptoms include lower abdominal pain, abdominal distention, and a palpable abdominal mass are also frequent presenting complaints. Many patients have clinical evidence of extensive extrauterine disease at initial presentation.

Grossly, carcinosarcomas present as a large, soft, friable polypoid tumors, involving endometrium and myometrium, and usually fill the endometrial cavity. Many of them are so large that they protrude through the external os. The surface is often smooth and the cut surface is more fleshy, variegated, hemorrhagic and necrotic.

MMT of the endometrium extends to the endocervix in about a quarter of cases. MMT may also arise in the cervix, where it growth as a polypoid neoplasm. Cervical MMT, compared to their counterparts in the corpus, are more commonly confined to the uterus at presentation, may have a better prognosis, and frequently have a nonglandular epithelial component.

Microscopically the tumor is composed of admixture of malignant epithelium (carcinomatous) and sarcomatous stroma, with latter usually predominating. The carcinoma component can include the full range of histologic variants. An adenocarcinoma of endometrioid type and poorly differentiated (often papillary serous) endometrial carcinoma usually predominant. The epithelial component of the tumor usually shows the most capability for invasion and metastases.

The sarcomatous component can be either homologous or heterologous. The homologous sarcomatous component is usually high grade and may consist of spindle cells, round cells or giant cells. Sometimes the stromal component resembles fibrosarcoma or leiomyosarcoma. The heterologous are those that contain chondrosarcoma, osteosarcoma or rhabdomyosarcoma.

Immunohistochemical staining for cytokeratin and epithelial membrane antigen (EMA) highlights the epithelial component. There is a generalized immunoreactivity for vimentin in the mesenchemal component. Occasionally mesenchymal components of MMT exhibit patchy positive staining with antibodies to cytokeratin and EMA, but this staining is less intense than is observed in the epithelial component of the tumor. Myoglobin is the most specific marker of rhabdomyoblastic differentiation but is also less sensitive. Immunoreactivity with desmin or muscle specific actin is also indicative of rhabdomyosarcoma. Foci of chondrosarcomatous differentiation are positive for S-100 protein.

The prognosis is extremely poor. Metastases occur early. Some studies suggest that having only homologous stroma elements have a slightly better prognosis than those with heterologous elements. Other studies suggest that there is no significant difference in prognosis. The prognosis is far more outweighed by the surgical pathological stage of disease and the stage is the single most significant prognostic factor. Positive peritoneal cytology is associated with unfavorable prognosis and shows extrauterine spread.

Total abdominal hysterectomy and bilateral salpingo-oophorectomy with pelvic lymphadenectomy is the treatment of choice. The response to radiation therapy and chemotherapy has been generally poor. The most common sites of recurrence are lung and abdominal cavity.


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Contributed by Irina Pushkar, MD and Uma NM Rao, MD

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