Navigating the International System for Reporting Serous Fluid Cytopathology in pericardial effusion: A meta‐analysis

The International System for Reporting Serous Fluid Cytopathology (TIS) provides a standardized framework for classifying serous fluid cytology into five diagnostic categories: nondiagnostic, negative for malignancy, atypical, suspicious for malignancy, and malignant. Although TIS has been widely adopted for pleural and peritoneal fluids, its application in pericardial effusion cytology remains limited. The objective of this study was to evaluate the use of TIS in pericardial effusion samples and estimate the associated risk of malignancy for each category.