Utility of Micronucleus Study on Breast Cytology Smears

Background Micronuclei (MN) are extranuclear chromatin bodies that arise due to chromosomal breakage and serve as biomarkers of genomic instability. Their presence has been linked to malignant transformation. Breast cytology offers a minimally invasive method for early detection of breast lesions. Evaluating micronuclei in these smears may enhance diagnostic accuracy by providing an additional objective parameter. Objective To compare the MN score in benign and malignant epithelial neoplasms of the breast as well as compare it within different grades of breast carcinomas. Method A retrospective cross-sectional study was conducted including epithelial breast neoplasms over a period of three years from February, 2021 to February, 2024. May- Grünwald-Giemsa (MGG) and Papanicolaou stained cytology smears of cases whose biopsy sample was also received in department of Pathology were included after ethical approval from institutional review committee. Micronuclei were identified based on established criteria and scored in 1,000 epithelial cells per case. The micronuclei frequency was compared across cytologically diagnosed benign and malignant lesions proven histopathologically. Statistical analysis was performed to evaluate significance. Result The mean micronuclei score was significantly higher in malignant smears compared to benign lesions (p < 0.05). A progressive increase in micronuclei frequency was observed from grade 1 to grade 3 amongst the malignant category. Conclusion Micronuclei scoring on breast cytology smears is a simple, cost-effective and potentially reliable marker of malignancy. It can serve as a useful adjunct in routine cytological evaluation, and also help in predicting the grade of malignancy.