Hidden bronchodilator responsiveness revealed after bronchoscopic removal of a tracheal lipoma: a case report.

BACKGROUND: Tracheal lipoma is an exceptionally rare benign airway tumor that may present with non-specific respiratory symptoms and mimic common obstructive airway diseases, resulting in delayed diagnosis and inappropriate treatment. We report a case of tracheal lipoma presenting as persistent wheeze and apparently non-reversible airflow obstruction, in which significant bronchodilator responsiveness became evident only after bronchoscopic intervention. CASE PRESENTATION: A 72-year-old lifelong non-smoker presented with a one-month history of progressive wheeze and exertional dyspnea that was refractory to standard inhaled therapy. Pulmonary function testing demonstrated severe obstructive ventilatory impairment without bronchodilator reversibility. Contrast-enhanced chest computed tomography revealed a well-circumscribed, low-attenuation, non-enhancing intraluminal lesion in the distal trachea, raising suspicion for a benign adipose tumor. Rigid bronchoscopy identified a broad-based tracheal mass occupying more than 70% of the airway lumen. Complete endoscopic resection was successfully performed using electrocautery snare excision combined with carbon dioxide cryotherapy. Histopathological examination confirmed tracheal lipoma. RESULTS: Following intervention, respiratory symptoms resolved rapidly, and airway patency was restored without complications. Pulmonary function improved substantially, with forced expiratory volume in 1 s (FEV1) increasing from 0.81 L to 1.49 L after bronchodilator administration. Notably, a previously negative bronchodilator test became markedly positive after tumor removal, obstructive airway physiology was relieved and BDR was unmasked. CONCLUSION: Bronchoscopic exploration shall be considered in patients presenting with persistent wheezing and poor response to routine treatment. Low-attenuation, non-enhancing tracheal lesions on CT may provide an important diagnostic clue. Rigid bronchoscopic intervention combined with electrocautery and cryotherapy is an effective minimally invasive treatment. This case highlights that fixed central airway obstruction can conceal underlying bronchodilator responsiveness, and relief of the obstruction may reveal clinically significant reversible airflow limitation.