Background: Solitary intraductal papillomas are benign, proliferative, mass-forming lesions arising in the lactiferous ductal system of the breast. Solitary intraductal papillomas are encountered with core biopsy of the breast, with an incidence of approximately 5%. Although papillomas are considered benign, the lesions frequently are surgically excised after diagnosis on core biopsy. Excision has historically been performed due to a certain percentage of core biopsy cases being reclassified (upstaged) to atypia or malignancy based on pathologic results of excisional biopsy.

Purpose: The objective of this study is to determine the incidence of solitary intraductal papillomas that were subsequently reclassified to atypia or malignancy following complete surgical excision.

Methods: A retrospective analysis was performed that included review of pathology results and other data for intraductal papillomas diagnosed by core biopsy from 2010 through 2016 at participating Milwaukee-metropolitan Aurora Health Care facilities. Female patients with documented personal history of breast carcinoma prior to the core biopsy procedure and patients under the age of 18 were excluded from the study. Reports were reviewed by 4 different investigators to identify subsequent excisional biopsy results as well as follow-up radiology to confirm diagnoses. All data were reported using descriptive statistics.

Results: Our initial review included 390 patients who had the diagnosis of papilloma from a core biopsy. Of those, 154 patients did not undergo excisional biopsy (39%). Of the 236 patients who had excisional biopsies, 203 patients had benign specimens (86%), 15 had atypia with intraductal papilloma (6%), 11 had adjacent atypia (5%), and 7 had malignancy (3%). The 7 patients with malignancy were reevaluated radiographically to assess for concordance of the core biopsy and excisional biopsy results. Of the 7, 3 patients with core biopsy-proven papilloma demonstrated malignancy within the existing lesion (1%) on subsequent excisional biopsy, and 4 patients were excluded due to lack of concordance between radiology and pathology findings comparing core biopsy location to excisional biopsy position.

Conclusion: In our facilities, only 1% of patients with initially diagnosed benign breast papillomas at core biopsy demonstrated true associated malignancy on the excisional biopsy specimen, a significantly lower rate than reported incidences in most similar previous studies. Our study is limited by our sample size. Further prospective studies would be helpful to further validate this data.