Cytohistological correlation in serous effusions using the newly proposed International System for Reporting Serous Fluid Cytopathology: Experience of an oncological center

Abstract

Background Cytological analysis is part of the initial etiological evaluation of serous effusions. The newly proposed International System for Reporting Serous Fluid Cytopathology (ISRSFC) aims to standardize reporting. Methods All pleural and peritoneal effusion samples admitted for cytological analysis at our institution between 2012 and 2016, and pericardial effusion samples admitted between 2008 and 2018, were reviewed and reclassified according to the ISRSFC. Risk of malignancy (ROM) and performance parameters were calculated. Results 1496 pleural effusion samples were reclassified: 12(0.8%) non‐diagnostic (ND), 944(63.1%) negative for malignancy (NFM), 9(0.6%) atypia of undetermined significance (AUS), 54(3.6%) suspicious of malignancy (SFM) and 477(31.9%) malignant (M). 64 pericardial effusion samples were reclassified: 23(35.9%) NFM, 1(1.6%) AUS, 4(6.3%) SFM and 36(56.2%) M. 763 peritoneal effusion samples were reclassified: 5(0.7%) ND, 457(59.9%) NFM, 12(1.6%) AUS, 37(4.8%) SFM and 252(33%) M. The ROM was, respectively, for each of the aforementioned categories, 57.1%, 23.9%, 50%, 76.2%, 100% in pleural effusions, 100%, 26.3%, 62.5%, 91.7%, 100% in peritoneal effusions and 0% for NFM, 0% for AUS and 100% for M in pericardial effusions. Sensitivity, specificity, positive predictive value, negative predictive value and diagnostic accuracy were, respectively, 61.6%, 100%, 100%, 73.3%, 81.3% for pleural, 100%, 100%, 100%, 100%, 100% for pericardial and 61.2%, 100%, 100%, 70%, 79.7% for peritoneal effusion samples. Conclusion Serous effusion cytology has a high specificity and positive predictive value and a modest sensitivity and negative predictive value, supporting its role in confirming the diagnosis of malignancy. The ISRSFC will increase standardization and reproducibility in reporting, leading to improved clinical decision‐making.

The International System for Reporting Serous Fluid Cytopathology: How to Incorporate Molecular Data in Cytopathology Reports

“…The expectation of finding malignancy in these samples is low, and an AUS diagnosis may be triggered by the detection of benign populations of macrophages or mesothelial cells with reactive or degenerative changes, but also from malignant cells, such as those from low-grade carcinomas or lymphomas. The reported ROM for this category varies between 13 and 100% with a mean ROM of 66% (±10.6%) [2,15]. The expected incidence for this is between 0.6-1.6% [15].…”

“…The reported ROMs for this category vary between 0 and 100%, with a mean ROM of 17.4% (±8.9%) [2]. The incidence rate of this diagnostic category should vary between 0.2 and 1% [2,15].…”

“…They provide useful information for appropriate clinical management and follow-up. The ROM for each has been estimated by a number of publications [2,15]. One must keep in mind, however, that since ROMs can vary between individual practices, ideally, each laboratory would perform its own assessment, reevaluating these values as needed.…”

“…This includes all diseases which lead to the development of benign serous effusions [11]. The reported ROM values for this category vary between 0 and 80% with a mean ROM of 21% (±0.3%) [2,15]. The incidence rate of this diagnosis varies between 70 and 80% [2,15].…”

“…The reported ROM for this category varies between 13 and 100% with a mean ROM of 66% (±10.6%) [2,15]. The expected incidence for this is between 0.6-1.6% [15]. AUS may be used as a place-holder category in a two-step reporting approach, pending ancillary tests [12].…”