Risk of malignancy after diagnosis of radial sclerosing lesion with associated atypia

PURPOSE: When a radial sclerosing lesion (RSL) with associated epithelial atypia is diagnosed on image-guided core needle biopsy, current guidelines recommend complete excision to exclude malignancy. Prior studies have reported that a substantial proportion of such lesions will be 'upgraded' to malignancy when surgical excision is undertaken. More personalized management may be possible if subgroups with lower risk of harboring malignancy are identified. METHODS: Following a systematic review of existing studies, we conducted an observational cohort study including all RSLs with associated atypia diagnosed on image-guided needle biopsy performed at our institution from 2020 to 2025. We estimated the cumulative incidence of malignancy at the RSL site in subgroups defined by the type of epithelial atypia and whether the atypia involved the RSL or was in the adjacent tissue. RESULTS: A total of 105 RSLs with associated atypia were included. Surgical excision was performed following biopsy diagnosis for 22 of 24 (91.7%) with atypical ductal hyperplasia (ADH) involving the RSL, 17 of 35 (48.6%) with ADH in the adjacent tissue, 16 of 20 (80.0%) with lobular neoplasia or other atypia involving the RSL, and 7 of 26 (26.9%) with lobular neoplasia or other atypia in the adjacent tissue. The remaining lesions underwent imaging surveillance. The cumulative incidence of malignancy at 3 years was 29.2% (95% CI: 15.1, 51.6%) for lesions with ADH involving the RSL; 8.6% (95% CI: 2.8, 24.3%) for lesions with ADH in the adjacent tissue; and 2.2% (95% CI: 0.3, 14.4%) for lesions with lobular neoplasia or other atypia. CONCLUSIONS: Lesions with ADH involving a RSL are likely to harbor malignancy. For other subgroups, the risk of malignancy is lower. These findings provide evidence that may be used to inform shared decision-making around imaging surveillance for selected patients with RSL and atypia on core needle biopsy.