B80-5-37 Cavitary Lung Adenocarcinoma Masquerading as Persistent Pneumonia

Abstract Introduction Lung adenocarcinoma can occasionally present with radiographic features that mimic infectious or inflammatory lung diseases. These atypical presentations may lead to delayed diagnosis and inappropriate treatment, particularly when initial imaging suggests pneumonia or abscess. This case illustrates the diagnostic challenge of distinguishing malignancy from infection in a patientwith persistent pulmonary cavitation despite appropriate antimicrobial therapy. Case Description A 76-year-old male with coronary artery disease post-CABG, type 2 diabetes, and prior myocardial infarction presented with dyspnea on exertion and chronic cough. Six weeks earlier, he had developed fever and cough while on a cruise, was diagnosed with pneumonia, and completed a 7-day course of levofloxacin. Despite treatment, symptoms persisted. Chest CT revealed right lower and left upper lobe infiltrates with cavitary lesions suspicious for abscess. He was admitted for further evaluation and underwent bronchoscopy with lavage and biopsy. Pathology showed only chronic inflammation, and cultures were negative. He was discharged on prolonged amoxicillin-clavulanate and fluconazole for presumed bacterial and fungal infection. Symptoms continued, prompting reevaluation. Expert review of the prior biopsy revealed atypical glandular structures concerning for malignancy. Repeat robotic bronchoscopy with transbronchial cryobiopsy confirmed adenocarcinoma, acinar pattern, with diffuse bilateral involvement. He was referred to oncology and initiated on pemetrexed and cisplatin. Discussion This case demonstrates the diagnostic difficulty of cavitary pulmonary lesions, where infection and malignancy often overlap radiographically. Cavitary adenocarcinoma is uncommon, comprising only 4-15% of cases, and can mimic abscess or tuberculosis 1,2. Multiple nondiagnostic biopsies delayed diagnosis in this patient, underscoring the limitations of conventional sampling in necrotic or fibrotic tissue. The diagnosis was achieved through cryobiopsy, which yielded larger, better-preserved specimens. Clinicians should maintain a broad differential diagnosis for nonresolving cavitary lesions and reconsider malignancy when infection fails to improve. This case emphasizes the importance of aggressive tissue sampling and multidisciplinary review to prevent delays in cancer recognition and treatment. References: 1. Chauhan D, Sharma V, Sharma A, et al. A case of lung adenocarcinoma presenting as multiple cavitary lung lesions. Arch Bronconeumol. 2019;55(7):422-424. doi:10.1016/j.arbres.2019.03.006.2. Watanabe Y, Kusumoto M, Yoshida A, Suzuki K, Asamura H, Tsuta K. Cavity wall thickness in solitary cavitary lung adenocarcinomas is an independent prognostic factor. Ann Thorac Surg. 2015;99(3):968-974. doi:10.1016/j.athoracsur.2014.10.040. pubmed.ncbi.nlm.nih.gov+1 This abstract is funded by: None