Risk Stratification of Atypical Breast Lesions Diagnosed on Core Needle Biopsy: Toward Selective Surgical Excision

Atypical ductal hyperplasia (ADH) and lobular intraepithelial neoplasia (LIN) identified on core needle biopsy have variable rates of upgrade to malignancy when surgically excised. Although excision is recommended for ADH, management of LIN has shifted toward a selective approach. We evaluated upgrade rates and developed a risk stratification model to guide management.

We conducted a retrospective study of 502 women diagnosed with ADH and/or LIN on core needle biopsy from 2020 to 2023 at an academic institution. Included patients underwent surgical excision or had at least 2-year follow-up. Upgrade rates to ductal carcinoma in situ (DCIS) or invasive carcinoma were assessed. Multivariable logistic regression identified predictors of upgrade.

Overall upgrade rates were 14.0% for ADH, 2.4% for LIN, and 18.0% for concurrent ADH+LIN (p<0.001). Among excised lesions, upgrades in ADH were predominantly DCIS (79.5%), whereas all upgrades in LIN were invasive carcinomas. All invasive cancers were low stage (stage IA). On multivariable analysis, age >70 years, prior contralateral breast cancer, dense tissue on mammography, and severe atypia were independent predictors of upgrade. Patients were stratified into low- (0 factors), moderate- (1 factor), and high-risk (≥2 factors) groups; upgrade rates were 4.2, 16.5 and 25.5%, respectively. Among patients managed nonoperatively, one ADH case was subsequently diagnosed as DCIS.

Upgrade risk in atypical breast lesions varies by lesion type and clinical factors. A risk-based approach identifies a subset of patients-particularly those with LIN or low-risk ADH-who may be managed without excision, potentially reducing unnecessary surgery while maintaining oncologic safety.