CHARACTERIZATION OF ABNORMAL CELL DIFFERENTIAL IN THORACENTESIS FOR MALIGNANT PLEURAL EFFUSIONS

Abstract

SESSION TITLE: Wednesday Abstract Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: 10/23/2019 09:45 AM - 10:45 AM PURPOSE: Malignancy is the second leading cause of pleural effusions in the US1 and account for approximately 125,000 hospital admissions per year2. Malignant pleural effusions are often diagnosed by cytology, but the turnaround time can be several days. Pleural fluid cell count differential is a routine part of pleural fluid analysis; results are obtained within a few hours, giving the clinician the opportunity to make patient care decisions before the definitive diagnosis is made. Pleural fluid cell differentials are typically obtained with automated cell counters, these counters cannot identify malignant cells. However, the presence of non-classifiable “other cells” may suggest a malignant diagnosis. METHODS: We performed a retrospective review of our institution’s internal database (Clinical Query 2) including all patients that underwent diagnostic and/or therapeutic thoracentesis from January 2016 to December 2018. Pleural fluid analysis and pleural fluid cytology were reviewed for all patients. Two groups were created based on the presence of “other cells” in the pleural fluid cell count differential. Atypical but non-diagnostic cytology was considered negative. A logarithmic regression analysis including the variables sex, active malignancy, heart failure, presence of other cells, exudate and glucose was performed. RESULTS: A total of 100 patients were included. The group of patients with “other cells” in pleural fluid had a total of 52 patients, within these patients, 28 had pleural fluid cytology positive for malignancy. The most common comorbidities were active malignancy, heart failure, chronic kidney disease and cirrhosis. The median time to obtain a cytology results was similar in both groups (3 vs 2.5 days). When pleural fluid parameters were compared between groups, it could be seen that the “other cells” group had a higher total number of cells (1243 vs 767.5, p=0.03), higher total protein (435 g/dL vs 355 g/dL, p<0.01), lower glucose levels (104 mg/dL vs 113.5 mg/dL, p=0.02), higher LDH (199 IU/L vs 150 IU/L, p=0.01), higher albumin (2.75 g/dL vs 2.1 g/dL, p<0.01) and higher cholesterol (81 mg/dL vs 53 mg/dL, p<0.01). Pleural fluid containing “other cells” was more likely to be exudative (43 vs 31, p=0.04); but more importantly a higher number of samples had malignant cytology (28 vs 4, p <0.01). When “other cells” are present in pleural fluid, the odds ratio for a malignant cytology result is 5.79 times higher than when these cells are absent (p= 0.01, CI=1.38-24.28). CONCLUSIONS: The presence of “other cells” in pleural fluid cell count differential increases the probability of a positive pleural fluid cytology for malignancy. CLINICAL IMPLICATIONS: This often-discarded value of the pleural fluid analysis holds potential as a screening tool for malignant pleural effusions. DISCLOSURES: Consultant relationship with Boston Scientific Please note: $1001 - $5000 Added 03/15/2019 by Alex Chee, source=Web Response, value=Consulting fee Consultant relationship with Boston Scientific Please note: $1001 - $5000 Added 03/16/2019 by Adnan Majid, source=Web Response, value=Consulting fee Consultant relationship with olympus Please note: $5001 - $20000 Added 03/16/2019 by Adnan Majid, source=Web Response, value=Consulting fee Consultant relationship with pinacle biologics Please note: $1001 - $5000 Added 03/16/2019 by Adnan Majid, source=Web Response, value=Consulting fee Consultant relationship with cook medical Please note: $1001 - $5000 Added 03/16/2019 by Adnan Majid, source=Web Response, value=Consulting fee No relevant relationships by Daniel Ospina-Delgado, source=Web Response No relevant relationships by Mihir Parikh, source=Web Response