B71-22 A Diagnostic Dilemma of a Cavitary Lung Lesion: Aspirated Foreign Body-Induced Post-Obstructive Pneumonia

Introduction Unusual pulmonary findings in adults with chronic lung disease can pose significant diagnostic challenges due to overlapping clinical and radiographic features between common and rare etiologies. Maintaining a broad differential and pursuing direct airway visualization when initial management fails to yield clarity remains critical. Clinical Presentation A 71-year-old male with an extensive smoking history and chronic obstructive pulmonary disease presented with a persistent, productive cough with thick purulent sputum and right-sided pleuritic chest pain, one month after treatment for presumed “walking pneumonia.” On presentation, the patient was afebrile, non-toxic appearing with an unremarkable physical examination. Imaging revealed a cavitary lesion in right middle lobe (RML), mediastinal and hilar lymphadenopathy, and partial thrombosis of a right pulmonary artery branch, raising suspicion for bronchiolitis obliterans organizing pneumonia (BOOP), pulmonary embolism (PE), or endobronchial malignancy with vascular invasion. Anticoagulation with intravenous heparin was started, which was later discontinued after PE was ruled out as an artifact on repeat imaging, while empiric antibiotics were continued. Autoimmune work up was obtained but remained negative. Bronchoscopy revealed an obstructing “glistening white” foreign body in the RML bronchus with purulent secretions, later identified as a retained nut, correlating with a choking episode during mixed nut ingestion six weeks prior. The foreign body was removed using a combination of suction and forceps. Bronchoalveolar lavage, bronchial and transbronchial biopsies were obtained which later came back negative for infection and malignancy. Endobronchial ultrasound revealed 1.2 cm right paratracheal lymph node with aspirates showing reactive inflammation. He was treated with amoxicillin-clavulanate and a steroid taper for post-obstructive pneumonia secondary to foreign body aspiration, with subsequent clinical and radiographic resolution. Discussion Cavitary lung lesions and persistent pulmonary opacities often raise concern for necrotizing infections, vasculitis, malignancy, and, less commonly, inflammatory conditions like BOOP. Cavitation is particularly concerning when associated with malignancy, with squamous cell carcinoma being the most common primary lung cancer to cavitate due to central necrosis. Mechanical airway obstruction may mimic these patterns through post-obstructive pneumonia and secondary parenchymal necrosis. Although rare in adults, foreign body aspiration is a noteworthy cause of airway obstruction, especially when the event is unwitnessed or forgotten. In cases where cavitary lesions persist despite empiric treatment or imaging reveals atypical features, early bronchoscopy is essential. Direct visualization can identify endobronchial obstructions, and prompt removal of an obstructing foreign body can lead to complete clinical and radiographic resolution while preventing unnecessary interventions or prolonged therapies. This abstract is funded by: N/A