The most frequent type of cancer originating in the uterine mucosa is endometrioid adenocarcinoma, designated as type 1 endometrial cancer.
|Uterine specimen with endometrioid carcinoma. Click to enlarge.
|Photomicrograph demonstrating deeply infiltrating endometrioid adenocarcinoma in the left picture. Click to enlarge.
Type 1 endometrial cancer appears in perimenopausal women. These tumors are related to increased and long-standing estrogen stimulation. In general, endometrioid adenocarcinomas have a good prognosis, but poorly differentiated (grade 3) tumors have a less favorable outcome, comparable to that for type 2 tumors.
Type 2 endometrial cancer is usually seen in older postmenopausal women (usually > 60 years of age) without any sign of long-standing estrogen stimulation, and mainly consists of serous papillary adenocarcinoma and clear cell carcinoma.
Correct subtyping of endometrial carcinoma requires well-trained pathologists with adequate experience in the field.
Additional methods are sometimes necessary to correctly diagnose these tumors, such as immunohistochemistry using antibodies against p53, estrogen receptors and others.
The histopathological classification (WHO)
- Endometrioid adenocarcinoma (75%–80%)
- Adenocarcinoma with squamous cell differentiation
- Adenosquamous carcinoma
- Serous papillary carcinoma (< 10%)
- Mucinous carcinoma (1%)
- Clear cell carcinoma (4%)
- Squamous cell carcinoma (< 1%)
- Mixed carcinoma (10%)
- Undifferentiated carcinoma
Mixed epithelial and mesenchymal tumor
These tumors include carcinosarcomas, which contain both malignant epithelial and a mesenchymal components. Adenosarcoma consists of a benign epithelial and malignant mesenchymal (sarcomatous) component.
Carcinosarcomas are classified as mixed, but are today considered as a variant of endometrial carcinoma. These tumors usually appear in older women and have a very poor outcome.
Adenosarcomas are now considered as a variant of sarcomas.