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undifferentiated endometrial carcinoma

Monday 27 June 2016

Definition: Undifferentiated endometrial carcinoma (UEC) is a distinct and extremely aggressive variant of endometrial carcinoma, which is included in the 2014 World Health Organization (WHO) Classification.

The WHO definition of UEC is that of “a malignant epithelial neoplasm with no differentiation”.

UEC is typically composed of diffuse sheets of dyscohesive, monomorphic epithelioid cells with moderate nuclear atypia, often with areas of geographic necrosis. Rhabdoid cells may be seen in a minority of cases.

UEC may occur in pure form or in association with a component of low grade endometrioid adenocarcinoma; this is referred to as dedifferentiated endometrial carcinoma.

Undifferentiated carcinoma of the endometrium is a high grade carcinoma and under-recognised, frequently diagnosed as grade 3 endometrioid carcinoma.

Undifferentiated carcinoma represents 9% of all endometrial carcinomas.

It is composed of solid sheets of epithelial cells and in most cases only 5-10% of the cells are positive for keratin.

The recognition of undifferentiated carcinoma is extremely important when this neoplasm is associated with a grade 1 or grade 2 endometrioid adenocarcinoma.

In this situation it is important to diagnose the solid areas of carcinoma as undifferentiated and avoid evaluating them as the solid component of endometrioid carcinoma because there is significant difference between the excellent prognosis of grade 2 endometrioid carcinoma, the intermediate prognosis of grade 3 carcinoma, and the poor prognosis of undifferentiated carcinoma, which in cases of association with differentiated areas should be diagnosed as dedifferentiated endometrioid carcinoma.

See also

- endometrial carcinomas