Radial Sclerosing Lesion (Radial Scar): Radiologic-Pathologic Correlation.

Radial sclerosing lesions (RS, also referred to as "radial scars") and complex sclerosing lesions (CSL) are uncommon breast lesions often grouped together as a single entity in practice. RS/CSL have an incidence of <0.1% to 1% at core needle biopsy (CNB). When detected on CNB, imaging and pathology features must be carefully evaluated to determine appropriate surgical management or imaging follow-up due to potential for malignant upgrade at surgery. Detection of RS/CSL has increased with the advent of tomosynthesis, in which an RS/CSL is typically detected as architectural distortion with or without associated mass with spiculated margins. On US, an RS/CSL is most often occult or manifests as subtle distortion with adjacent cysts. Imaging findings cannot distinguish benign RS/CSL from those upgraded to malignancy at surgery, although larger lesion size may be associated with higher upgrade rates. Histologically, an RS has a central fibroelastotic nidus with entrapped-appearing ducts and proliferative changes at the periphery appearing to radiate from the center; CSL are larger than RS, more disorganized, and typically include multiple patterns of epithelial proliferations, including sclerosing adenosis, sclerosing papillomas, usual ductal hyperplasia, and cysts. RS/CSL with associated atypia at CNB have a 16%to 29% rate of upgrade to malignancy on surgical excision, thus rendering surgical excision essential. Conversely, an RS/CSL without associated atypia, particularly when ≤1 cm in size, has <3% rate of upgrade to malignancy at surgery, allowing consideration of imaging follow-up in lieu of excision. Here, we review recent literature as well as radiology and pathology findings of RS/CSL.