Background: Breast cancer is the leading cause of cancer deaths among women worldwide. Fine needle aspiration cytology (FNAC) and breast ultrasound are pivotal in characterization of a breast lump as benign and malignant lesion. The main objectives were to categorise the Breast FNAC samples according to new system of reporting and to assess the Risk of malignancy (ROM), sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and diagnostic accuracy for all categories.Methods: A Total of 900 FNAB cytology specimens from January 2017 to December 2018 were obtained. These were reclassified according to newly proposed IAC Yokohama system of reporting. The ROM, sensitivity, specificity, Positive Predictive Value (PPV), Negative Predictive Value (NPV) and diagnostic yield of Breast FNAC and also of ultrasound were calculated.

Assessment of proliferation is a means of predicting local recurrence and metastatic potential of malignancies. A mitotic count is not an ideal marker for proliferation in certain situations, such as salivary gland neoplasms. Ki-67 expression as a proliferation marker has been investigated in many human tumors. In the present study, Mitotic index (MI) and Ki-67 index were studied in pleomorphic adenoma, basal cell adenoma, mucoepidermoid carcinoma, adenoid cystic carcinoma epithelial myoepithelial carcinoma, carcinoma ex Pleomorphic adenoma and adenocarcinoma of salivary glands. The results were compared.The MI was similar in benign neoplasms, mucoepidermoid carcinoma and epithelial myoepithelial carcinoma, whereas it was high in carcinoma ex pleomorphic adenoma, adenocarcinoma and adenoid cystic carcinoma. The Ki-67 index was different in basal cell adenoma and pleomorphic adenoma. It was helpful in differentiating high grade and low grade mucoepidermoid carcinoma. It highlighted the malignant behavior of epithelial myoepithelial carcinoma.It was concluded that Ki-67 in benign neoplasms is 5% or less and in malignant ones more than 23% with a few exceptions. In mucoepidermoid carcinoma and epithelial myoepithelial carcinoma, Ki-67 index was found to be a better indicator for aggressiveness. These findings will be presented in this paper, with review of literature.

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