Core Biopsy Diagnosis vs. Excision Diagnosis of Papillary Lesions of the Breast: The Impact of Breast Pathology Subspecialization.
Kiran Jakate, Marina Debrot, Frances P O'Malley, Anna Marie Mulligan. University of Toronto, ON, Canada; St. Michael's Hospital, Toronto, Canada
Background: Classifying papillary lesions of the breast on core biopsy (CB) can be challenging. The extent to which subspecialty training in breast pathology might mitigate such difficulties has not yet been reported. We investigated change in diagnoses upon surgical excision according to subspecialist training in breast pathology as well as interobserver agreement between specialized breast (BP) and non-breast pathologists (NBP) in classifying these lesions.
Design: CB of 259 papillary lesions from 245 patients diagnosed between 2000-2010 were classified by both a BP and NBP into benign, atypical, DCIS/encapsulated papillary carcinoma (EPC) or invasive. Rates of change in diagnostic category in the surgical excision specimen were calculated for BP and NBP. Comparisons were performed using Χ2 test. Kappa values were calculated for interobserver agreement.
Results: Of 156 lesions with subsequent excision, 81 were originally diagnosed as benign, 39 atypical, 26 DCIS/EPC and 10 invasive on CB. There was no significant difference between BP and NBP in the rate of upgrade from benign to atypical/malignant diagnoses; although, downgrades from atypical/malignant to benign were more commonly seen for NBP (P=0.002)(Table 1). Overall, the BP CB diagnosis was less likely to differ from the excision diagnosis (P=0.0001).
|Change in Diagnosis||NBP N(%)||BP N(%)||P-value|
|Benign to atypical||10(6.4)||11(7.1)||1.0|
|Benign to malignant||14(9)||6(3.8)||.11|
|Atypical to malignant||23(15)||17(11)||.40|
|Atypical to benign||10(6.4)||2(1.3)||.04|
|Malignant to benign||5(3.2)||0||.07|