Clinical History:

A 38-year-old woman had heavy, irregular menstrual bleeding. She had been taking estrogen-containing medications for several years. She was treated with endometrial curretage followed by hysterectomy.

There is too much endometrium, irregularly arranged, with many dilated (cystic) glands, a so-called "Swiss cheese" pattern. There is also much more endometrial stroma accompanying even those glands deep in the myometrium. Thus, there is a hyperplasia of stroma and epithelium. The glandular epithelium is crowded and multilayered but most cells are without significant cellular atypism.

Questions:

1. What is the significance of the pathologic finding in this setting?

This hyperplasia could represent a preneoplastic condition. However, the greatest risk would come from an "atypical" hyperplasia.

2. How does this process differ from neoplasia?

The hyperplasia is potentially reversible, and may be under physiologic control (e.g., the amount of estrogenic stimulation), whereas a neoplasm is an autonomous, uncontrolled growth. Sometimes the distinction is difficult to make on a small biopsy sample or on cytology. The hyperplasia could be "atypical" and show changes similar to that of a neoplasm. Conversely, a neoplasm could be well-differentiated and resemble normal or hyperplastic tissue.