Role of Agnor Staining in Diagnosis of Malignant Serous Effusions – A Cross-Sectional Study

Background: Serous effusions are the fluids accumulated in body cavities like the pleural, pericardial, and peritoneal cavities. Detection of malignant cells in these effusions helps in staging and planning the course of management. Accurate identification of the malignant cells using conventional cytological examination is a diagnostic challenge. Argyrophilic nucleolar organiser regions (AgNORs) are a simple cytological technique that is useful for detecting these malignant cells in effusions. Hence, in the present study, the silver staining method is applied to differentiate malignant cells from reactive mesothelial cells in serous effusions. The objective is to determine the significance of AgNOR staining in differentiating benign and malignant serous effusions and to determine the prevalence of malignant changes in serous effusions. Material and Methods: This is a sectional study conducted from August 2022 to December 2023 in the Department of Pathology at Basveshwara Medical College and Hospital. This study includes serous effusions sent to the central lab for cytological examination. All samples were centrifuged, and smears were prepared and stained with H&E and AgNOR. AgNORs are counted as black dots in the nuclei of 100 cells using 100x oil immersion. The pattern of AgNOR dispersion and its shape will be compared in reactive and malignant cases. Results: Out of 310 samples, 176 were ascitic, and 134 were pleural fluids. Prevalence of malignancy in these samples was 11.95%. Mean agnor count in NFM was 2.33 +/- 0.67, AUS was 5.68 +/- 1.99, SFM was 7.87 +/- 2.25, and in malignancy was 11.04 +/- 0.9, indicating that the mean count is higher in malignant cells than in benign cells. Benign cells had Agnor dispersion of 0-1+, and malignant cells had dispersion of 2+- 3+. Similarly, benign cells had an average size of 0-1+ and malignant cells had an average size of 2+-3+. Agnor size had a sensitivity of 91.89%and a specificity of 97.76% in detecting malignant cells. Agnor dispersion had a sensitivity of 94.59%and a specificity of 99.1% in detecting malignant cells. Conclusion: Mean Agnor count is significantly elevated in malignant cells when compared to benign cells. Along with increased size and dispersion of Agnor, a count is seen in malignant cells of serous effusion. Agnor stain is a particularly useful and rapid diagnostic test for differentiating benign from malignant cells when routine cytology fails. Keywords: AgNor staining, serous effusions: Agnor size, Agnor dispersion.