Background: Micronuclei (MN) scoring has been used as a biomarker of chromosomal damage, genome instability and cancer risk. Micronuclei scoring can be exploited in the screening of high risk population of a specific cancer. Aims: 1. to score the micronuclei in the fibroadenomas and infiltrating ductal carcinoma (IDC). 2. To compare the micronuclei scores in fibroadenomas and various grades of infiltrating ductal carcinomas. Methodology: A retrospective study was done in the Department of Pathology including thirty cases of fibroadenoma and thirty cases of infiltrating ductal carcinoma. Micronuclei scoring was done on Papanicolaou and Hematoxylin and Eosin stained smears of these cases. Carcinoma were graded by Robinson cytological grading. Statistical analysis was done to assess the difference in MN scoring between the Fibroadenoma group and IDC. Results: Mean micronuclei score range was 1.9±1.7 in Fibroadenoma and 25.1±11.7 in Infiltrating duct carcinoma. It was 20.2±10.3, 23.1±9.5 and 29.9±12.4 in IDC cytological grades 1,2 and 3 respectively. Statistical analysis showed significant increase in MN score in ductal carcinoma when compared with fibroadenoma.

Keywords: Micro Nuclei; Fibroadenoma; Infilreating Ductal Carcinoma.