CD44s as a surrogate marker for distinguishing intraductal papilloma from papillary carcinoma of the breast

Background-It has been shown that CD44 variants are differentially expresse d in normal and neoplastic breast tissues. The diagnostic value of these ma rkers in distinguishing benign from malignant breast lesions has not been w ell examined. Aims-To evaluate the diagnostic value of CD44s in distinguishing between in traductal papillomas and papillary carcinomas of the breast, which may be d ifficult morphologically. Methods-Expression of CD44s detected by immunohistochemistry was studied in a series of intraductal papillomas (11) and papillary carcinomas (10). The normal breast tissues surrounding the lesions of these cases served as a c ontrol. The number of CD44s positive epithelial cells was scored and catego rised as < 10%, 10-70%, or > 70%. Results-Normal breast epithelial cells and all intraductal papillomas (11 o f 11) expressed CD44s in a high proportion of cells (> 70%). In contrast, t he majority of papillary carcinoma cases (eight of 10) expressed this marke r in < 10% of the cells. In the remaining two papillary carcinoma cases, po sitivity was seen in more than 10% but still less than 70% of the cells. Conclusions-CD44s detection by immunohistochemistry is useful in distinguis hing intraductal papillomas from papillary carcinomas of the breast.