Risk of malignancy after diagnosis of radial sclerosing lesion without atypia

Surgical excision of radial sclerosing lesions (RSLs) has historically been recommended to rule out malignancy. Contemporary guidelines support imaging surveillance instead whenever these lesions are "adequately sampled." However, uncertainty exists around what suffices for sampling prior to observation, and the outcomes of imaging surveillance.

We conducted an observational cohort study including all RSLs diagnosed on image-guided needle biopsy performed at our institution from 2020 to 2025. We excluded lesions with a concurrent diagnosis of invasive cancer, ductal carcinoma in situ, or epithelial atypia in the ipsilateral breast. For lesions that underwent repeat percutaneous biopsy or surgical excision, we estimated the probability that additional sampling revealed malignancy. For the entire population, whether excision was performed or not, we estimated the cumulative incidence of malignancy at the site of RSL during follow-up.

A total of 419 RSLs were diagnosed in 390 patients. 262 (62.5%) lesions were diagnosed by stereotactic-guided vacuum-assisted biopsy (VAB), 100 (23.9%) by MRI-guided VAB, and 57 (13.6%) by ultrasound-guided core needle biopsy. During initial work-up or follow-up, 35 lesions underwent repeat image-guided biopsy and 28 underwent surgical excision. None of these additional sampling procedures revealed malignancy. The estimated 3-year cumulative incidence of malignancy at the RSL site was 0% (95% CI: 0, 2.0%).

These findings support a management strategy of imaging surveillance when radiologic-pathologic concordance is established. Even for less extensively sampled lesions, routine repeat biopsy or surgical excision may not be necessary for RSLs without atypia.