LOW YIELD OF CYTOLOGY FOR DIAGNOSIS OF MALIGNANT PLEURAL EFFUSION RELATED TO SQUAMOUS CELL LUNG CANCER

Abstract

SESSION TITLE: Lung Cancer SESSION TYPE: Original Investigation Posters PRESENTED ON: 10/10/2018 01:00 PM - 02:00 PM PURPOSE: Malignant pleural effusion (MPE) is an ominous development of metastatic cancer that portends a dire prognosis. Some effusions are challenging to diagnose with pleural fluid cytology alone and necessitate pleural biopsy. The aim of this study was to assess the yield of pleural fluid cytology for diagnosis of malignancy secondary to metastatic squamous cell lung cancer as compared to bronchogenic adenocarcinoma. METHODS: We performed a retrospective review of patients with non-small cell lung cancer (NSCLC) who developed pleural effusions to evaluate the diagnostic yield of pleural fluid cytology from serial thoracentesis and pleural biopsy. With institutional review board approval (IRB Pro00091556) we identified MPE cases by reviewing referrals for tunneled pleural catheter placement or pleuroscopy in addition to screening cytopathology reports. RESULTS: Among 36 NSCLC patients with MPE, the initial diagnostic sensitivity of first thoracentesis to diagnose MPE was 66.7%, which improved to 71.4% with second thoracentesis, and 88.2% with pleural biopsy. Yield of pleural fluid cytology for diagnosis of malignancy was 11.1% vs. 85.2 % for squamous cell vs. adenocarcinoma (chi-square test p-value <0.0001). The diagnostic yield of pleural biopsy via pleuroscopy for squamous cell vs. adenocarcinoma was 66.7% vs. 92.9% (chi-square test p-value =0.52). 94.1% of all malignant effusions from NSCLC were classified as exudative by Light’s criteria. CONCLUSIONS: Yield of pleural fluid cytology for diagnosis of metastatic squamous cell lung cancer is low compared to bronchogenic adenocarcinoma. CLINICAL IMPLICATIONS: Clinicians should be aware of the low diagnostic sensitivity of pleural fluid cytology in patients with squamous cell lung cancer. These patients should be referred for pleural biopsy to confirm the diagnosis of an exudative effusion even when pleural fluid cytology is unrevealing. DISCLOSURES: Advisory Committee Member relationship with Leica Biosystems Please note: $5001 - $20000 Added 03/02/2018 by Rajesh Dash, source=Web Response, value=Travel Board Member relationship with College of American Pathologists Please note: $5001 - $20000 Added 03/02/2018 by Rajesh Dash, source=Web Response, value=Travel No relevant relationships by Kevin Davidson, source=Web Response No relevant relationships by Kamran Mahmood, source=Web Response