Can additional immunohistochemistry staining replace the surgical excision for the diagnosis of papillary breast lesions classified as benign on 14-gage core needle biopsy?

To evaluate whether the upgrade-to-malignancy rate of benign papillary lesions on ultrasonographically (US)-guided 14-gage core needle biopsy (CNB) can be decreased using immunohistochemistry staining (IHC) for pathologic diagnosis, and to determine whether additional IHC can replace surgical excision for the diagnosis of papillary breast lesions classified as benign on 14-gage CNB. A total of 274 consecutive papillary lesions were studied, including available imaging findings, CNB specimens and surgical specimens. Two rounds of retrospective review of the pathologic slides from CNB were performed by a pathologist, including H&E staining (first round; 1R, n = 274) and IHC of the benign papillomas (second round; 2R). The upgrade-to-malignancy rate was assessed for benign papillomas with comparison between 1R and 2R. The final diagnosis was based on surgical pathology. The clinicoradiologic findings were compared between the benign and malignant papillomas at the time of final diagnosis. In 1R, 204 benign papillomas were identified. During 2R using IHC, three carcinomas and ten atypical papillomas were diagnosed. Among the 204 benign papillomas from 1R, 15 were found to be carcinomas (upgrade-to-malignancy rate, 7.4 %) at the time of final diagnosis. With 2R, the overall upgrade-to-malignancy rate was decreased to 4.7 % (9/192, p = 0.3680). Older age and upgrades made after IHC review resulted in higher upgrade-to-malignancy rates (odds ratio, 4.133, 95 % CI 1.393–12.267, p = 0.0106; 134.46, 95 % CI 17.886–infinity, p < 0.0001, respectively). The use of IHC may decrease the upgrade-to-malignancy rate for benign papillary lesions after US-guided 14-gage CNB and help to more accurately predict malignancy at the time of surgery. Despite these findings, a misdiagnosis still occurred in our study, suggesting that IHC cannot replace surgical excision for diagnosis of benign papillary lesions of the breast.