Radial Scar: What the Radiologist Needs to Know at the End of 2021

Nearly one million breast biopsies are carried out every year in the United States of which 70% are benign.1 Of the benign lesions, some are viewed as a precursor to breast cancer and/or associated with increased risk of future breast cancer.2-5 Such lesions are regarded as high-risk or borderline lesions,6 which represent an increasing number of observations among core needle biopsies, mainly thanks to more efficient imaging techniques and/or larger needle size.7 About 10% of core needle biopsies show a high-risk lesion with the vast majority of these lesions in women in their 40s.8 Currently, the high-risk classification consists of radial scar/complex sclerosing lesion, papillary lesions, lobular carcinoma in situ (LCIS), columnar cell lesions (hyperplasia or flat epithelial atypia), and atypical hyperplasia (lobular and ductal). In 1999, Alleva et al. described radial scars (RSs) as not truly scars; instead, they were idiopathic entities unrelated to prior surgery or trauma with proposed possible causes that included localized inflammatory reaction and chronic ischemia with subsequent slow infarction.9 Cardenosa has described RSs as being rosette-like proliferations that are most often seen in women between 41-60 years.10 Classically, the term complex sclerosing lesion (CSL) refers to a radial scar greater than 10mm.10 The prevalence of RS ranges from 0.1-2/1,000 with screening mammography. How-ever, it has been reported to be present in 2-16% of mastectomy specimens.11 In addition, the range of incidental RS on autopsy varies from 14 to 28%.12-15 In this article, we will provide a review of RS. In addition, the imaging appearance of RS will be described. Finally, we will focus on current outcomes and provide an update on its management based on the most recent recommendations.