Usual ductal hyperplasia

Usual ductal hyperplasia (UDH) is a benign lesion of the breast wherein cells look very similar to normal. It is a spectrum of changes that can range from minimal stratification of cells to proliferations that are just short of atypical ductal hyperplasia.

Usual ductal hyperplasia with small cells that lack atypia.

Histopathology of usual ductal hyperplasia (UDH) on H&E stain and immunohistochemistry. As seen on higher magnification H&E stain at left, it has the usual irregular "slit-like" lumina. However, this case had almost moderate atypia with somewhat enlarged vesicular nuclei in the periphery, and therefore immunohistochemistry was performed that confirmed UDH:
- Estrogen receptor showing heterogeneous positivity, rather than the diffusely positive expression seen in atypical ductal hyperplasia (ADH)
- CK 5/6 with a mosaic pattern, predominantly in the central zone, rather than the negative expression seen in ADH
- E-cadherin and p120 showing membranous staining, rather than being negative and cytoplasmic, respectively, in lobular carcinoma in situ
- Myoepithelial cell stain (calponin in this case) showing circumferential staining, rather than the absent staining seen in breast cancer.

Histopathology

Usual ductal hyperplasia is typically a cohesive proliferation with haphazard, jumbled cell arrangement or streaming growth pattern. Cells have mild variation in cellular and nuclear size and shape.