THE PLEURA THICKENS: LUNG ADENOCARCINOMA PRESENTING AS PSEUDOMONAS EMPYEMA

Abstract

SESSION TITLE: Fellows Lung Cancer Posters SESSION TYPE: Fellow Case Report Posters PRESENTED ON: October 18-21, 2020 INTRODUCTION: Pleural empyema is a collection of pus in the pleural cavity and symptoms include: chest pain, shortness of breath, fever, and other systemic symptoms. Persistent infection within the pleural space can lead to inflammation and the formation of scar tissue known as fibrothorax. Empyema as a primary finding in lung malignancies has been reported in less than 0.3% of patients; however, a recent observational study showed patients with empyema are at an increased risk for developing cancer within five years. CASE PRESENTATION: A 50-year-old man presented with left sided chest and back pain. At the time of presentation, he was tachypneic and tachycardic but otherwise his physical exam was unremarkable. His history was notable for heavy tobacco use and a recent admission four months prior for a left-sided pseudomonas oryzihabitans empyema requiring chest tube placement and a prolonged course of antibiotics. Pleural fluid cytology during initial admission was negative for malignant cells. In the interim, the patient had repeat imaging that showed pleural thickening but complete resolution of the effusion. During the present admission, the patient underwent chest computed tomography angiography (Figure 1) that showed increased pleural thickening and nodularities, so he underwent a pleural biopsy that showed no evidence of malignancy or infection. He was treated with intravenous antibiotics, but the abnormal pleural findings persisted (Figure 2). Cardiothoracic surgery was consulted for video assisted thoracoscopic surgery and decortication. Intraoperative findings were notable for pleural adhesions, pleural thickening, and malignant-appearing pleural nodules on the surface of the parietal pleural. Frozen sections were concerning for adenocarcinoma of the lung which was later confirmed by immunohistochemical studies. DISCUSSION: Empyema is a rare presentation of lung malignancy, especially in the absence of an obstructing mass causing a post-obstructive pneumonia. Cell types observed in chronic empyema-associated malignancies include: lymphoma, squamous cell carcinoma, mesothelioma, sarcoma, and rarely adenocarcinoma4. Multiple studies have shown high variability in the sensitivity of pleural fluid cytology for detecting malignancy, although the sensitivity for detecting malignant pleural effusions caused by adenocarcinoma is higher than other malignancies . Furthermore, pleural thickening or fibrothorax is a known complication of chronic empyema and is monitored with serial imaging. This case illustrates the importance of further evaluation of pleural thickening in patients with significant risk factors and persistent symptoms. CONCLUSIONS: Pleural empyema is an uncommon primary presentation of lung cancer. Diagnosing a an empyema can cause anchoring bias and missed diagnosis of malignancy in the absence of a discreet mass or positive cytology. Reference #1: Froeschle P, Wanke W, Granetzny A. Video-thoracoscopy and staged management of preoperative empyema in lung cancer. Thorac Cardiovasc Surg. 2005; 53: 188–90. Reference #2: Teng CJ, Hu YW, Yeh CM, Chen TJ, Liu CJ. Cancer Risk in Patients With Empyema: A Nationwide Population-Based Study. Medicine (Baltimore). 2016;95(9) Reference #3: Loveland P, Christie M, Hammerschlag G, Irving L, Steinfort D. Diagnostic yield of pleural fluid cytology in malignant effusions: an Australian tertiary centre experience. Intern Med J. 2018 Nov;48(11):1318-1324. doi: 10.1111/imj.13991. PubMed PMID: 29869427.v DISCLOSURES: No relevant relationships by Mohamed Abdalla, source=Web Response Unrestricted grant for CME research relationship with AstraZeneca Please note: $20001 - $100000 Added 05/31/2020 by Sandra Adams, source=Web Response, value=Grant/Research Support Unrestricted grant for CME research relationship with Boehringer Ingelheim Please note: $20001 - $100000 Added 05/31/2020 by Sandra Adams, source=Web Response, value=Grant/Research Support Unrestricted grant for CME research relationship with GlaxoSmithKline Please note: $20001 - $100000 Added 05/31/2020 by Sandra Adams, source=Web Response, value=Grant/Research Support Unrestricted grant for CME research relationship with Sunovion Please note: $20001 - $100000 Added 05/31/2020 by Sandra Adams, source=Web Response, value=Grant/Research Support Support for continuing medical education relationship with Mylan/Theravance Please note: $1001 - $5000 Added 05/31/2020 by Sandra Adams, source=Web Response, value=nebulizer/meds for teaching No relevant relationships by Connor McDonald, source=Web Response No relevant relationships by Jay Peters, source=Web Response No relevant relationships by Paloma Sanchez, source=Web Response