Comparing the expression of myoepithelial cell markers CD10 and smooth muscle actin with the estrogen receptor status in the invasive carcinoma breast: An immunohistochemical study

Background: Breast cancer is the most frequent cancer in females throughout the world. Around 20% of breast carcinomas are estrogen receptor alpha (ER)-negative. Thus, theoretically this negativity could be either the result of down-regulation of ER expression in the tumor cells, or the result of the tumor being derived from cells which normally lack that expression. Normal basal, including myoepithelial cells of the breast is ER-negative. CD10 and smooth muscle actin (SMA) are used as markers for the demonstration of these basal cells. Aims: To compare the expression of positive staining for CD10 and SMA in ER-negative and ER-positive invasive breast carcinomas. Materials and Methods: The study was performed on 40 paraffin-embedded tissues of already diagnosed cases of invasive breast carcinomas with known ER status, i.e., thirty ER-negative and ten ER-positive cases. Expression of CD10 and SMA was demonstrated using avidin-biotin-peroxidase complex (ABC) technique. Tumor was considered to be positive for both markers only when more than 10% of tumor cells were stained positive. Results: Overall, CD10 tumor cell staining was seen in eight, 23.3% (7/30) ER-negative cases and in 10% (1/10) ER-positive cases. Also the staining intensity was considered to be strong. SMA tumor cell staining was seen in only 6.7% (2/30) ER-negative cases and the staining intensity was considered to be moderate. Percentages of positively stained tumor cells varied between 13% to 72% and 23% to 45% for CD10 and SMA, respectively. Conclusion: CD10 is a better marker when compared to SMA, as it is expressed in more number of cases and gives strong positivity in tumor cells. Higher expression of CD10 and SMA is correlated with higher tumor grade and ER negativity.