TY - JOUR T1 - HLA-DR and β<sub>2</sub> microglobulin expression in medullary and atypical medullary carcinoma of the breast: histopathologically similar but biologically distinct entities JF - Journal of Clinical Pathology JO - J Clin Pathol SP - 286 LP - 291 DO - 10.1136/jcp.53.4.286 VL - 53 IS - 4 AU - Meora Feinmesser AU - Aaron Sulkes AU - Sara Morgenstern AU - Jaqueline Sulkes AU - Sidi Stern AU - Elimelech Okon Y1 - 2000/04/01 UR - http://jcp.bmj.com/content/53/4/286.abstract N2 - Aims—To examine the expression of HLA-DR and β2 microglobulin in medullary carcinoma and atypical medullary carcinoma of the breast to determine if the effective presentation of tumour antigens to the immune system can differentiate between these two histopathologically similar entities. Methods—Expression of HLA-DR and β2 microglobulin was examined by immunohistochemical methods in five samples of medullary carcinoma of the breast, which has a relatively favourable prognosis, six samples of atypical medullary carcinoma of the breast, which has a prognosis closer to that of regular invasive duct carcinoma, and 20 samples of invasive duct carcinomas, 10 with an accompanying lymphocytic infiltrate. Results—A positive and significant correlation was found between tumour type and both HLA-DR and β2 microglobulin expression. Expression was most prominent in medullary carcinoma, followed by atypical medullary carcinoma and invasive duct carcinoma with and without lymphocytic infiltrates. The mean intensity and percentage of HLA-DR tumour immunostaining were significantly higher in medullary carcinoma than in the other three tumour groups, as was the mean intensity of β2 microglobulin immunostaining. Mean percentage of β2 microglobulin immunostaining was significantly higher in medullary carcinoma than in invasive duct carcinoma without lymphocytic infiltrates, and showed a trend to increase from invasive duct carcinoma with lymphocytic infiltrates to atypical medullary carcinoma and medullary carcinoma. Conclusions—Medullary carcinoma and atypical medullary carcinoma of the breast differ in their expression of HLA-DR and β2 microglobulin. The relatively favourable prognosis of medullary carcinoma of the breast may be related to effective tumour antigen presentation to the immune system through MHC-I and MHC-II expression. Immunotherapy aimed at MHC-I and MHC-II induction might have a beneficial effect in breast cancer. ER -