Diagnosis and characterization of malignant effusions through pleural fluid cytological examinationPorcel, José M.Current Opinion in Pulmonary Medicine: July 2019 - Volume 25 - Issue 4 - p 362–368 doi: 10.1097/MCP.0000000000000593 DISEASES OF THE PLEURA: Edited by Richard Light Buy Abstract Author InformationAuthors Article MetricsMetrics Purpose of review Malignancy accounts for a substantial proportion of pleural effusions, and cytologic examination of pleural fluid is the easiest way to establish the diagnosis. This review summarizes relevant advances in the diagnostic cytopathology of pleural effusions for the practicing pulmonologist. Recent findings Cytologic analysis using a stained smear and cell block preparation is able to provide the diagnosis in about 55% of malignant effusions. Processing a maximum of two separate specimens (provided the initial examination is negative) with an approximate volume of 40 ml each is the most accepted recommendation. Cytologic identification of mesothelioma is particularly challenging, but testing for BAP1 nuclear expression (immunocytochemistry) and p16 deletion (fluorescence in situ hybridization) has greatly improved our diagnostic capabilities. Similarly, in patients with advanced nonsmall cell lung cancer a comprehensive molecular testing on pleural fluid samples, which should include at a minimum epidermal growth factor receptor/v-raf murine sarcoma viral oncogene homolog B/anaplastic lymphoma kinase/reactive oxygen species 1/programmed death-ligand 1 alterations, is highly advocated to identify patients who may benefit from targeted therapies. Summary A judicious use of pleural fluid cytologic specimens, which includes immunocytochemistry and molecular testing, eliminates the need for more invasive tissue sampling. Department of Internal Medicine, Pleural Medicine Unit, Arnau de Vilanova University Hospital, IRBLleida, Lleida, Spain Correspondence to José M. Porcel, MD, FACP, FCCP, FAPSR, Department of Internal Medicine, Pleural Medicine Unit, Arnau de Vilanova University Hospital, Avda Alcalde Rovira Roure 80, Lleida 25198, Spain. Tel: +34 973248100; e-mail: firstname.lastname@example.org Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.