This small group of tumours contain features of both epithelial and mesenchymal tissues. The most common is carcinosarcoma; this is frequently described as maligant Müllerian mixed tumours by pathologists and oncologists.
Usually a disease of elderly women who are post menopausal; median age is 65. They are uncommon but notable for aggressive behaviour.
The aetiology of carcinosarcoma is unclear; there has been a suggestion that tamoxifen use may have a relationship with the development of this tumour.
The tumour frequently forms a large uterine mass and spreads through lymphatics to the retroperitoneum.
Most patients present with post-menopausal bleeding; more advanced cases present with a pelvic mass or systemic symptoms and signs.
Imaging may often demonstrate a large lesion with extensive myometrial involvement; metastases to adnexal structures are not uncommon.
Unlike the endometrial carcinomas, carcinosarcoma is frequently haemmorhagic and necrotic. The growth of mesenchymal tissues such as bone or cartilage may cause increased firmness.
There are two components to the carcinosarcoma:
- The epithelial component may resemble any of the endometrial carcinomas, including the high grade types such as clear cell or serous carcinoma; most frequently it resembles endometriod carcinoma.
- The mesenchymal component is often high grade, undifferentiated sarcoma; leiomyosarcoma or endometrial stromal sarcoma are also possible
- There may be bone or cartilagenous tissue present
The epithelial component stains with cytokeratin markers; the mesenchymal component with vimentin. TP53 status is usually identical between the two components, re-inforcing their common clonal origin.
Current thinking considers carcinosarcoma as an aggressive endometrial carcinoma with areas of mesenchymal differentiation. It has similar patterns of spread to the high grade endometrial carcinomas; metastatic deposits are usually of carcinoma elements only.
Staging / Classification
Staging of carcinosarcoma is the same as the endometrial carcinomas.
Other Mixed Tumours
Adenosarcoma is an uncommon sarcoma that has a benign epithelial component and malignant mesenchymal component. They are usually exophytic but may cause the uterus to enlarge significantly. Patients present with vaginal bleeding or pelvic mass. The course of the disease is variable; it is usually of low malignant potential but may recur locally in up to 30-40% of patients.
Other mixed tumours exist but are very rare; they all consist of benign or malignant epithelial and mesenchymal components.