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.
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.
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![Usual ductal hyperplasia: 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.[1]](https://upload.wikimedia.org/wikipedia/commons/thumb/3/3d/Histopathology_of_usual_ductal_hyperplasia%2C_annotated.png/1280px-Histopathology_of_usual_ductal_hyperplasia%2C_annotated.png?utm_source=en.wikipedia.org&utm_campaign=parser&utm_content=thumbnail)
