LAUSR

BACKGROUND Distinguishing between a breast intraductal papilloma and a papillary lesion with atypia or malignancy can be very challenging on core biopsy. There has been a long ongoing debate over whether or not it is necessary for breast papillary lesions diagnosed on core biopsies to be surgically excised, and the upgrading rate after excision varies. METHOD AND/OR RESULT This study was carried out in a subspecialized academic pathology department, with well-formed criteria established among the faculty for the categorization of breast papillary lesions, with emphasis on the morphology evaluation of cellular features. A total of 320 breast core biopsies with follow-up excisions were identified. Of these, 286 cases had concordant results between the biopsy and excision, giving a concordance rate of 89.4%, with 98% concordance (143/146) in benign papilloma, 100% (111/111) in papillary carcinoma, and 51% (32/63) in papilloma with atypia. Of the upgraded cases, two were upgraded from benign to atypical, 11 from atypia to malignancy, and only one from benign to malignant. The overall average upgrading rate was 4.4% (14/320), with the critical upgrading (from benign to atypia or malignancy) rate of 0.94% (3/320). Downgrading was only identified in the group of papilloma with atypia, with 20 of 63 cases downgraded to benign papilloma on excision. CONCLUSION Our study indicates that surgical excision may not be necessary for all papillary lesions after detailed evaluation of the morphology on core biopsies. Assessing the morphological features of the epithelial cells is critical for the accurate classification and clinical management of papillary lesions.