General
Usual Ductal Hyperplasia (UDH) is a proliferative breast disease consisting of a non-clonal heterogeneous population of cells that can occur within areas of FCC
Slightly increased risk (1.5-2x normal) for breast cancer if >4 layers of epithelial cells are present.
Histology
Multilayered epithelial cells (mixture of cell types) that nearly completely fill and expand the ducts/acini
Increased myoepithelial cells (spindled nuclei)
Overlapping/streaming nuclei of the myoepithelial cells and epithelial cells that form a vague fascicle
Irregularly shaped & peripherally located secondary lumens
NO ATYPIA of epithelial cells (no pleomorphism)
NO NECROSIS
Useful Stains
Normal ducts & lobules have a subset of ER-positive cells
Express a heterogeneous staining pattern with CK5/6; LMWCK & HMWCK (heterogenous cell population)
ADH is generally positive for LMWCK (red cytoplasm) but NEGATIVE for HMWCK (brown cyt. staining in ME cells) and CK5/6
Keep in Mind:
There is a big difference in calling something usual ductal hyperplasia (no increased risk for breast cancer) vs. atypical ductal hyperplasia or ductal carcinoma in situ (both have an inc risk for breast cancer). We will discuss more about ADH in the next post.
The clear presence of well defined ME layer is reassuring in calling something benign. However, the presence/absence of myoepithelial cells is not as valuable for intraductal processes since some intraductal carcinomas retain some degree of myoepithelial cells around the periphery; these ME cells are usually attenuated or partially lost in tumor cells.
When to call UDH
There is obvious apocrine metaplasia
Streaming of nuclei
HMW keratin (CK903; aslo called 34bE12) and CK5/6 are generally POSITIVE in UDH
Keep in mind that some invasive carcinomas express CK5/6 (have a basal phenotype; negative for ER/PR/Her2; more aggressive)
Summary
Heterogeneous population of cells- diff shapes & sizes
Multilayered epithelial cells that nearly completely fill and expand the ducts/acini
Secondary lumens are irregularly shaped & peripherally located
NO epithelial cell atypia (no pleomorphism)
Increased myoepithelial cells (spindled nuclei)
Overlapping/streaming nuclei of the myoepithelial cells and epithelial cells that form a vague fascicle
Continue to the next post to learn the criteria for calling "atypical" ductal hyperplasia.