External Validation of a Pragmatic Scoring System for Predicting Upgrade of Atypical Ductal Hyperplasia at the Time of Surgery.

[BACKGROUND] Atypical ductal hyperplasia (ADH) carries a variable risk of upgrade at the time of surgery to ductal carcinoma in situ (DCIS) or invasive malignancy. We sought to externally validate a pragmatic upgrade risk scoring system previously demonstrated to have an upgrade rate of 0-2% in patients with a risk score of 0 out of 5.

[METHODS] A multicenter, retrospective review of all percutaneous biopsies containing ADH was performed from 2017 to 2023. Women aged ≥ 18 years who underwent diagnostic mammography and surgical excision for pathologic correlation were included.

[RESULTS] Among the 183 cases included, the mean age was 58 years ± standard deviation 11, and 91 patients (50%) reported a family history of breast cancer. Most biopsies were stereotactic (75%), vacuum-assisted (84%), and used 9-gauge needles (73%). Three of 14 (21%) patients with a risk score of 0 were upgraded to DCIS following surgical excision. Seven (19%) patients had a risk score of 1 upgraded - six to DCIS and one to an estrogen receptor-positive/progesterone receptor-positive/human epidermal growth factor receptor 2-negative invasive ductal carcinoma measuring 5.45 mm in largest diameter. On multivariate analysis, age, mammographic lesion size, and suspicion of DCIS on biopsy were predictive of upgrade.

[CONCLUSIONS] The risk model evaluated generally predicts the risk of upgrade of ADH at excisional biopsy but may underestimate the upgrade rate in the lowest-risk cohort. Because of the small sample size, further work is needed to determine whether the rate of upgrade is truly low enough in this lowest-risk cohort to recommend against excisional biopsy.