Flat Ductal Intraepithelial Neoplasia Diagnosed at Stereotactic Core Needle Biopsy: Is Excisional Biopsy Indicated?

OBJECTIVE. This study correlates ductal intraepithelial neoplasia (DIN) 1A diagnosed at stereotactic spring core needle biopsy (CNB) or vacuum-assisted biopsy (VAB) with the subsequent surgical histologic results or long-term follow-up imaging findings to predict the likelihood of upgrade to ductal carcinoma in situ (DCIS) or invasive carcinoma. MATERIALS AND METHODS. Stereotactic imaging-guided CNBs and VABs were performed principally for assessment of microcalcifications seen on mammography. DIN 1A diagnoses made at CNB or VAB were correlated with subsequent excisional biopsy results or imaging follow-up. Patients were included only if there was no concomitant CNB or VAB diagnosis of DIN 1B, atypical lobular hyperplasia, lobular carcinoma in situ or DCIS, papillary lesion, or invasive carcinoma. Surgical biopsy results were obtained for 239 patients. Upgrade was defined as a diagnosis of DCIS or invasive carcinoma at surgery. Patients who did not undergo surgical excision were followed with imaging. RESULTS. An upgrade rate of 4.2% (10 lesions in 239 patients) is reported. The remaining samples (229/239) had a surgical diagnosis of DIN 1A or DIN 1B, lobular carcinoma in situ, or a benign finding with no atypia. CONCLUSION. The upgrade rate of DIN 1A diagnosed at CNB or VAB was 4.2%. These results indicate it may be reasonable to avert immediate surgery in favor of short-term imaging follow-up.