Context

The International System for Reporting Serous Fluid Cytopathology has developed a standardized system of reporting serous effusion cytology by classifying them into five categories- Non-Diagnostic (ND), Negative for Malignancy (NFM), Atypia of Undetermined Significance (AUS), Suspicious for Malignancy (SFM) and Malignant (M). Very few studies have been conducted so far to confirm the risk of malignancy of the different categories.

Aims

The main objectives of our study were to classify serous effusions acoording to the International System for Reporting Serous Fluid Cytopathology (ISRSFC) and assess risk of malignancy and performance parameters.

Materials and Methods

All serous effusion samples received from January 2019 to December 2020 were reclassified according to the ISRSFC. Using histopathological diagnosis as gold standard, risk of malignancy (ROM) and performance parameters were calculated.

Results

831 pleural effusion samples were reclassified: 3(0.4%) ND, 635 (76.4%) NFM, 65 (7.8%) AUS, 60 (7.2%) SFM and 68 (8.2%) M. 457 peritoneal effusion samples were reclassified: 5(1.1%) ND, 368(80.5%) NFM, 19(4.2%) AUS, 17(3.7%) SFM and 48(10.5%) M. All 12(100%) pericardial effusions belonged to NFM category. The ROM was respectively, for each of the aforementioned categories, 0%, 2.1%, 33.3%, 94.1%, 100% in pleural effusions, 50%, 4.8%, 22.2%, 83.3%, 100% in peritoneal effusions and 0% for NFM in pericardial effusions.

Conclusion

The ISRSFC is an excellent system for accurately classifying serous effusions with greater reproducibility of reports and better communication between pathologist and clinician.