Is Surgical Excision Mandatory for Sclerosing Adenosis Diagnosed on Core Needle Biopsy? Multimodal Imaging Features and Upgrade Outcomes in a Symptomatic Cohort

Background: Sclerosing adenosis (SA) is a benign, proliferative breast lesion that frequently mimics malignancy on multimodality imaging. The appropriate clinical management of SA diagnosed via core needle biopsy (CNB) remains a highly debated topic in breast oncology. This study aimed to evaluate the clinical, imaging, and histopathological characteristics of CNB-diagnosed SA-spectrum lesions and to determine the rate of, and factors associated with, pathological upgrade at the time of surgical excision in a symptomatic cohort. Methods: This retrospective, single-center study evaluated 34 symptomatic female patients who received a CNB diagnosis of SA. Patients were assessed using targeted ultrasound (US, n = 34), digital mammography (n = 19), and/or dynamic contrast-enhanced breast MRI (n = 17). Based on CNB findings, lesions were classified as isolated SA, complex/accompanied SA, or atypical SA. Patients subsequently underwent either definitive surgical excision or long-term imaging surveillance. Upgrades were defined as the presence of a high-risk B3 lesion not identified on CNB (Level 1) or overt malignancy, such as ductal carcinoma in situ or invasive carcinoma (Level 2), at final surgical pathology. Results: Twenty-one patients (61.8%) underwent surgical excision, while thirteen (38.2%) were managed with radiological follow-up (median surveillance 16 months, range 7–84). Within the surgical cohort, 9 of 21 patients (42.9%; 95% CI: 24.5–63.5%) demonstrated an upgrade: 6 (28.6%; 95% CI: 13.8–50.0%) to a B3-level lesion and 3 (14.3%; 95% CI: 5.0–34.6%) to malignancy. Notably, two of the three malignant upgrades originated from lesions initially classified as isolated SA without atypia on CNB. Due to the limited sample size, no single clinical or imaging variable (BI-RADS category, lesion size, or age) reached statistical significance as an independent predictor of upgrade (all p > 0.10). All patients managed with imaging surveillance remained radiologically stable. Conclusions: In stark contrast to the 1–2% upgrade rates traditionally reported in asymptomatic screening populations, symptomatic SA-spectrum lesions selected for surgical excision following CNB exhibited a substantially higher overall upgrade rate (42.9%) and malignant upgrade rate (14.3%) in our cohort, albeit with wide confidence intervals reflecting the modest surgical subgroup size. The occurrence of malignant upgrades from presumed isolated SA underscores the limitations of CNB sampling and highlights the necessity of multimodality imaging–pathology concordance. Because this estimate derives exclusively from patients already selected for surgery on the basis of clinical and imaging suspicion, it reflects the upgrade risk of this pre-selected, imaging-discordant subgroup and should not be extrapolated to the baseline risk of all CNB-diagnosed SA. Accordingly, these findings caution against extending non-operative management without further scrutiny to symptomatic SA cases showing a similar degree of imaging–pathology discordance: in such cohorts, surgical excision or large-volume vacuum-assisted excision may still merit consideration despite the absence of atypia on CNB, although this observation is drawn from a small, non-randomly selected surgical subgroup and should be interpreted with corresponding caution.