 The histopathology of endometrial cancers is highly diverse. The most common finding is a well-differentiated endometrioid adenocarcinoma, which is composed of numerous, small, crowded glands with varying degrees of nuclear atypia, mitotic activity, and stratification. This often appears on a background of endometrial hyperplasia. Frank adenocarcinoma may be distinguished from atypical hyperplasia by the finding of clear stromal invasion, or "back-to-back" glands which represent nondestructive replacement of the endometrial stroma by the cancer. With progression of the disease, the myometrium is infiltrated.
