Micronucleus and Its Significance in Effusion Fluids

BACKGROUND: Micronucleus (MN) is an extranuclear body within the cell formed due to failure of incorporation of whole chromosomes or their fragments during cell division. MN scoring can be done to identify malignant effusions. AIMS: This study aimed to score micronuclei to distinguish malignant effusion from benign effusions and to correlate MN score with type of malignant effusion. METHODS AND MATERIALS: A retrospective study was conducted on 30 malignant and 30 benign effusions. The number of micronucleated cells per 1,000 cells was counted in effusion smears stained with Papanicolaou stain under oil immersion (1,000×). RESULTS: The mean MN score in malignant effusions was 3.77 with standard deviation (SD) of 2.13. The mean MN score in benign effusions was 0.50 with SD of 0.57. The difference in MN score between malignant and benign effusions is statistically significant (P < 0.001). A cut-off MN score of 6.5 was seen to distinguish malignant and benign effusions with 100% specificity and 100% sensitivity in this study. CONCLUSIONS: MN score is higher in malignant effusions when compared with benign effusions. This can be used to differentiate malignant effusions from benign effusions in low resource setting.