Malignant mixed Mullerian tumor of the uterus

Malignant mixed Müllerian tumor (MMMT) of the uterus, also known as uterine carcinosarcoma, is the commonest (up to 50%) type of uterine sarcoma. They are thought to account for 2-8% of all malignant uterine cancers . The uterus is the commonest site for malignant mixed Müllerian tumors .

Pathology

A uterine malignant mixed Müllerian tumor can be either homologous or heterologous.

Similar to malignant mixed Müllerian tumors in general, they are composed or both carcinomatous (epithelial) and sarcomatous (mesodermal) components. Usually, the epithelial component dominates .

Prevalent subtypes for the epithelioid component include:

Prevalent subtypes for the sarcomatoid component include:

  • undifferentiated sarcoma: homologous tumors
  • rhabdomyosarcoma: heterologous tumors

Radiographic features

A uterine malignant mixed Müllerian tumor commonly presents as an intracavitary mass with coexistent dilatation of the endometrial canal.

Ultrasound

Often hyperechoic on ultrasound .

CT

Often heterogeneously hypodense and ill-defined on contrast-enhanced CT . Dilatation of the uterine cavity can be appreciated in the vast majority of cases.

MRI

They are not considered to have a pathognomonic appearance on MRI, with appearances often indistinguishable from those of endometrial adenocarcinoma.

However, reported general signal characteristics include .

  • T1: predominantly isointense to both myometrium (~75%) and endometrium (~70%)
  • T2
    • hyperintense to myometrium (~90%) 
    • either hypointense (~55%) or isointense (~41%) to the endometrium
  • C+ dynamic contrast
    • <1 min: hypointense (~40%) or isointense (33%) to myometrium
    • 1-4 min: hypointense (~60%) to myometrium  
    • >4 min: isointense (56%) to myometrium

Treatment and prognosis 

Like other malignant mixed Müllerian tumors, they are highly aggressive tumors and carry a poor prognosis.

Differential diagnosis

General considerations include:

See also