Application of the international system for reporting serous fluid cytopathology on pleural effusion cytology with paired pleural biopsy: A new insight and novel approach on risk of malignancy

The risk of malignancy (ROM) remains an area of interest for further evaluation in reporting systems including in International System for reporting serous fluid cytopathology (TIS), which is a standardized system for reporting effusion cytology. Herein, we report our findings in further investigation of ROM in TIS by studying on paired pleural effusion specimens and corresponding pleural biopsies with emphasis on negative for malignancy, and atypia of undetermined significance categories.