Abstract Introduction Lung cancer remains the leading cause of cancer-related mortality worldwide, with non-small-cell lung carcinoma (NSCLC) accounting for approximately 85% of cases. Although typical symptoms include cough, hemoptysis, dyspnea, and weight loss, NSCLC may present atypically as non-resolving pneumonia or lung abscess, leading to diagnostic delay. This is particularly challenging in smokers with chronic obstructive pulmonary disease (COPD), in whom infectious etiologies are often presumed. Additionally, epidemiological studies have suggested an association between peptic ulcer disease (PUD) and increased NSCLC risk, possibly through shared inflammatory or carcinogenic mechanisms. Case Presentation A 69-year-old man with COPD, heavy tobacco use, and chronic alcohol consumption presented with productive cough, progressive dyspnea, melena, hematochezia, and low-grade fever. Examination revealed wheezing and decreased air entry over the left lower lung field. Chest radiography showed left lower lobe consolidation with an adjacent soft-tissue density, interpreted as community-acquired pneumonia (CAP). He was treated with amoxicillin-clavulanate, azithromycin, and prednisone for presumed CAP with COPD exacerbation. One month later, he returned after a syncopal episode with persistent dyspnea. Repeat chest CT demonstrated a left lower lobe pulmonary abscess with surrounding consolidation and a 5-mm non-calcified right apical nodule. Infectious workup was negative except for Streptococcus pseudopneumoniae on Karius testing and neutrophilic leukocytosis. Despite prolonged antibiotic and corticosteroid therapy, his symptoms and imaging abnormalities persisted. Bronchoscopy performed two months after the initial presentation revealed an endobronchial mass obstructing the left lower bronchus. Cytology from bronchoalveolar lavage showed atypical squamous cells, and biopsy confirmed squamous cell carcinoma of the lung. Concurrent evaluation for gastrointestinal bleeding revealed gastric and duodenal ulcers on upper endoscopy. Discussion This case underscores the diagnostic challenge of NSCLC masquerading as a pulmonary abscess or non-resolving pneumonia. Approximately 1% of lung cancers initially mimic lung abscesses, often delaying diagnosis and management. In patients with significant smoking history and COPD, persistent consolidation despite adequate therapy should prompt early bronchoscopy. The coexistence of peptic ulcers raises the possibility of a biological link between PUD and NSCLC, potentially mediated by chronic inflammation, smoking, and shared carcinogenic pathways. Conclusion In high-risk patients, non-resolving pneumonia warrants early bronchoscopy to exclude malignancy. Awareness of atypical presentations—such as pulmonary abscesses with concurrent gastrointestinal pathology—can facilitate timely diagnosis and improve outcomes in NSCLC This abstract is funded by: None
Chahal et al. (Fri,) studied this question.