RESUMEN
<p><b>OBJECTIVE</b>To investigate the expression of high-molecular-weight keratins CK5/6, CK14, estrogen receptor (ER) and progesterone receptor (PR) in differential diagnosis of simple ductal hyperplasia (UDH), atypical ductal hyperplasia (ADH) and low-grade ductal carcinoma in situ (low-grade DCIS) .</p><p><b>METHODS</b>The clinicopathological data of twenty cases of atypical ductal epithelial hyperplasia (ADH) with focal cancerization changed into low-grade DCIS diagnosed at Tianjin Medical University Cancer Institute and Hospital between January 2013 and February 2014 were reviewed and analyzed. The expressions of CK5/6, CK14, ER and PR were detected by immunohistochemistry.</p><p><b>RESULTS</b>Positive expressions of CK5/6 and CK14 were seen in UDH showing a mosaic pattern, while negative expression in ADH and low-grade DCIS. In addition, CK5/6 and CK14 were positively expressed in the myoepithelial cells of UDH, ADH and low-grade DCIS. Positive expressions of ER and PR were observed in UDH, ADH and low-grade DCIS. But they presented diffuse and homogeneous strong positive expression in ADH and variable positive expression in UDH.</p><p><b>CONCLUSION</b>In the intraductal proliferative lesions of the breast, the use of combined detection of the expression of CK5/6, CK14, ER and PR is of practical significance in the differential diagnosis of UDH, ADH and low-grade DCIS.</p>