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Key Words: Breast; Papillary lesions; Needle core biopsy; Cytokeratin 8/18; Cytokeratin 5; p63
DOI: 10.1309/AJCPXV64GXLZCIGA
ABSTRACT
Objectives: Immunohistochemical markers have been shown to assist in the stratification of breast papillary lesions. We evaluated the ability of different cytokeratin (CK) and p63 expression profiles on needle biopsy specimens to predict excision diagnoses.
Methods: A CK5/p63/CK8/18 antibody cocktail was applied to 58 needle biopsy specimens (32 papillomas, 7 atypical papillomas, 19 papillary carcinomas on excision).
Results: p63 expression was greater in papillomas than in atypical papillomas (P = .044) and papillary carcinomas (P< .0001). Papillary carcinomas and atypical papillomas showed greater CK8/18 expression (and conversely less CK5 expression) than did papillomas (P < .0001). Negative or focal p63 expression was 96% sensitive for diagnosing any atypical lesion (atypical papilloma or papillary carcinoma) on excision, whereas CK8/18 predominant expression (?80% cells) was 100% sensitive. In contrast, the sensitivity of the original diagnosis was only 81%. The greatest accuracy for the diagnosis of atypical papillary lesions (95%) was achieved when both p63 and cytokeratins were used in combination in an algorithmic fashion. This method also correctly identified all cases that had papillary carcinoma (100% sensitivity) on excision.
Conclusions: Although a single stain or combination cannot independently stratify papillary lesions, a CK5/p63/ CK8/18 antibody cocktail is a useful adjunct to morphology for evaluating breast papillary lesions in needle biopsy specimens.
Intraductal papillary lesions of the breast have been categorized as papilloma, atypical papilloma (intraductal papilloma with atypical ductal hyperplasia [ADH] or ductal carcinoma in situ DCIS]), and papillary carcinoma (papillary DCIS and intracystic/encapsulated papillary car- cinoma1,2), depending on both the presence or absence of myoepithelial cells and the appearance of the epithelial component.2,3 Among other features, papillomas typically demonstrate a well-developed row of myoepithelial cells covering the papillary cores with overlying nonatypical epithelial cells; atypical papillomas are mostly similar except for the presence of a variable amount of atypical epithelium; papillary carcinomas, however, usually lack myoepithelial cells and the entire proliferative epithelium is atypical. Based on these features, Mulligan and O'Malley3 proposed an algorithmic approach to the diagnosis of papil- lary lesions of the breast in which the presence and distribu- tion of myoepithelial cells is first determined, followed by characterization of the nature of the epithelial component.
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