OBJECTIVETo evaluate the expression of cytokeratins in intraductal proliferative lesions of breast, including usual ductal hyperplasia (UDH), atypical ductal hyperplasia (ADH), ductal carcinoma-in-situ (DCIS) and its role in differential diagnosis.

METHODSNinety two cases of paraffin-embedded lesional breast tissue, 30 cases of frozen samples, cell cultures of hyperplastic ductal cells and 2 invasive ductal carcinoma cell lines (T47D and MCF-7) were used for this study. Immunohistochemistry was performed using EnVision method for 34betaE12, CK8 and CK14.

RESULTSThe percentage of 34betaE12-positivity in paraffin-embedded samples of UDH, ADH, DCIS and invasive ductal carcinoma (IDC) was found to be 95.2%, 33.3%, 19.2% and 12.5% respectively. In frozen tissues, all UDH cases and 55% of IDC cases expressed 34betaE12. The primary UDH cell cultures and T47D cell line were also 34betaE12-positive, whereas MCF7 cell line showed negative staining. The expression rate of CK8 and CK14 in UDH was also different from that in ADH and DCIS.

CONCLUSIONS34betaE12 can be useful in differential diagnosis of intraductal proliferative lesions of the breast. However application of this cytokeratin stain in intraoperative frozen sections is relatively limited. The expression patterns of CK8 and CK14 are also helpful in the differential diagnosis of similar lesions.