Breast, Radial scar with florid epithelial hyperplasia

Radial scar (“radial sclerosing lesion”) is a benign breast lesion that can be mass forming. It is not a true scar, in that it is not associated with trauma or prior surgery. Rather, it is a growth of otherwise benign glandular elements, with associated stromal fibrosis and architectural distortion.

The histologic features are of a benign proliferation of tubular glands having preserved myoepithelial and luminal layers. An overall “sclerosing adenosis-like” architecture can usually be seen, associated with dense stromal fibrosis, or a central fibrotic core. The appearance correlates well with radiologic and sonographic findings of a hypoechoic stellate mass. The epithelial component can be proliferative, either with benign hyperplasia (as in this case), or with neoplastic cells (atypical hyperplasia or in situ carcinoma, not seen in this case). In some cases, the features (both pathologic and radiologic) can be difficult to distinguish from invasive carcinoma.