P-cadherin as myoepithelial cell marker for differential diagnosis of benign and malignant breast lesions

Background: P-cadherin is cell-cell adhesion glycoprotein which can be used as a myoepithelial cell (MEC) marker in the breast lesions. MEC layer is retained in most benign lesions and loss of this outer layer is hallmark of infiltrating carcinomas in the breast. Aim: To evaluate the expression of P-cadherin as MEC marker in the differential diagnosis of benign and malignant breast lesions. Materials and Methods: Immunohistochemical staining was done using P-cadherin-specific antibody on formalin fixed paraffin-embedded sections of 25 benign and 15 malignant breast lumps. Results: All 25 cases of benign breast lesions showed positive P-cadherin immunostaining, while only 4 out of 15 cases of infiltrating ductal carcinoma showed positive immunostaining for P-cadherin. In the case of benign lesions, staining index varied from 4 to 6 or 7 to 9, while in case of malignant lesions, 11 cases showed staining index from 1 to 3. Only 4 out of 15 malignant cases had staining index from 4 to 6. None of them showed index from 7 to 9. Conclusions: P-cadherin as a MEC marker can be used in differentiating benign and malignant breast lesions.