Collagenous endobronchial obliteration after chemoradiation followed by consolidation osimertinib: a case report.

INTRODUCTION: Consolidation osimertinib after concurrent chemoradiation is a standard treatment for unresectable stage III EGFR-mutated NSCLC, but endobronchial toxicity has not been well described. To our knowledge, this is the first reported case of collagenous endobronchial obliteration after concurrent chemoradiation therapy and consolidation osimertinib. CASE PRESENTATION: We report an 83-year-old woman who developed acute dyspnea and complete right-lung atelectasis 3 months after completion of concurrent chemoradiation therapy while receiving consolidation osimertinib. Bronchoscopy showed membranous occlusion of all three right lobar bronchi, and biopsy demonstrated dense collagenous tissue admixed with fibrin and mild inflammation. Systemic glucocorticoid therapy and temporary interruption of osimertinib led to initial clinical improvement, but the obliteration recurred during corticosteroid tapering. DISCUSSION: Compared with previously reported cases, our case demonstrated a more advanced fibrotic process, together with extensive involvement of all three right lobar bronchi within the irradiated field. Notably, this fibrotic change developed earlier than is typical for radiation-induced fibrosis. While radiation-induced airway injury was the principal cause, the early onset raises the possibility that osimertinib also contributed by impairing epithelial repair through EGFR inhibition. CONCLUSIONS: Clinicians should be aware of the potential for collagenous endobronchial obliteration, particularly in patients with centrally located tumors receiving chemoradiation followed by consolidation osimertinib. Bronchoscopic evaluation may facilitate diagnosis, whereas systemic glucocorticoid therapy with gradual tapering and close monitoring may aid management in similar cases.