Diagnostic Value of Cytokeratin 5 and Cytokeratin 6 in Benign and Malignant Lesions of Breast

Background: Correlation of Cytokeratin 5 and Cytokeratin 6 expression in benign and malignant lesions of the female breast-ducts and to find out the utility of Cytokeratin 5/6 in the prognosis of carcinoma breast. Methods: The present study was carried out on 78 benign and malignant lesions of breast. Tissues were fixed in formal saline, processed for paraffin sections and stained with Haematoxylin and Eosin (H&E) stain. Immunohistochemical staining was performed using mouse antihuman polyclonal D5/16B4 antibody for cytokeratin 5/6 and visualization obtained with DAB and the slides were examined for staining pattern (cytoplasmic or membrane), proportion and intensity of staining of tumour cells. Results: Amongst the 78 cases of breast lesions, 38 (48.7%) cases were benign breast disease, 18 (23.1%) were ductal carcinoma in situ and 22 (28.2%) cases were of malignant breast carcinoma. Out of 22 cases of malignant breast disease, 16 (72.7%) cases showed negative cytokeratin reaction with staining score of  <2 and 6 (27.3%) cases of triple negative breast carcinoma (TNBC) showed positive cytokeratin expression with staining score  of 5-8. Conclusions: Immunohistochemistry is efficiently used for differentiating the UDH (usual-ductal-hyperplasia) from the DCIS (ductal carcinoma in situ), ruling out micro-invasion, distinguishing invasive carcinoma from pseudo-invasive lesions, identifying breast cancer histological sub-type and molecular phenotype.