OBJECTIVETo evaluate the diagnostic approach and criteria for intraductal papillary neoplasms of breast.

METHODSAccording to the criteria of 2003 WHO classification, 187 cases of intraductal papillary neoplasm of breast were identified and enrolled into the study. The clinical and histologic features were reviewed and immunohistochemical study for CD10, p63, CK14, CK5/6, CK7, MGB1 and p53 were carried out on 53 cases.

RESULTSAmongst the 187 cases studied, there were 128 cases of intraductal papilloma, 16 cases of atypical intraductal papilloma and 43 cases of intraductal papillary carcinoma. They showed a spectrum of morphologic features including epithelial and stromal hyperplasia and secondary changes. The expression of myoepithelial markers, including CD10 and p63, significantly decreased in ascending order from intraductal papillomas, atypical intraductal papillomas and intraductal papillary carcinomas (P < 0.001). The expression of basal cell markers, including CK5/6 and CK14, showed a mosaic pattern in benign lesions and significantly decreased or was absent in atypical and carcinomatous lesions (P < 0.001). In contrast, the luminal cell marker CK7 expressed in the three groups with no statistically significant difference (P = 0.06). On the other hand, the expression of MGB1 in intraductal papillary carcinomas was much lower than that in the other two groups (P = 0.002 and P = 0.007). The staining for p53 was negative in all of the three groups.

CONCLUSIONSIntraductal papillary neoplasms of breast represent a heterogeneous group of lesions with various morphologic appearances. Correlation with immunostaining results for myoepithelial markers, basal-type cytokeratins and luminal epithelial markers are helpful in arriving at a definitive diagnosis.