Abstract Background With recent advances in oncology, tyrosine kinase inhibitors like imatinib play a significant role in gastrointestinal stromal tumor (GIST) treatment but can cause rare pulmonary complications. When new respiratory symptoms arise after starting these agents, differentiating drug toxicity from other lung diseases is important for timely management. Case Presentation A 72-year-old man with GIST, recently started on imatinib, presented with acute dyspnea and hypoxia. His medical history included chronic obstructive pulmonary disease and a 40-pack-year smoking history. Chest CT revealed new bilateral interstitial infiltrates absent on imaging two months ago, prior to imatinib initiation. The differential diagnosis included imatinib-induced pneumonitis versus atypical infection. Bronchoscopy showed yellowish nodular mucosa throughout the trachea and bronchi, mucus plugging, and airway narrowing in the left lower lobe. Endobronchial biopsies demonstrated amyloid deposits consistent with tracheobronchial amyloidosis. The bronchoalveolar lavage was negative for infection and, therefore, corticosteroid therapy was initiated, resulting in clinical and radiographic improvement. The findings supported a diagnosis of imatinib-induced pneumonitis coexisting with tracheobronchial amyloidosis. Discussion This case highlights the diagnostic challenges when drug-induced pneumonitis occurs along with structural airway abnormalities. Tracheobronchial amyloidosis, although rare, can cause airway obstruction and coexist with inflammatory lung conditions. The temporal association with imatinib, exclusion of infection, and steroid responsiveness indicate imatinib-induced pneumonitis as the primary cause of the acute symptoms, with concurrent amyloid deposition contributing to airway pathology. Conclusion In patients developing new pulmonary symptoms after starting tyrosine kinase inhibitors, drug-induced pneumonitis should be strongly suspected. The coexistence of airway diseases such as tracheobronchial amyloidosis can complicate diagnosis and management, highlighting the need for thorough evaluation including bronchoscopy and tissue biopsy to guide treatment. This abstract is funded by: None
Dhungel et al. (Fri,) studied this question.