Large endotracheal tumour presenting as severe COPD: flow-volume loop analysis, not always a straightforward diagnostic test.

The flow-volume loop (FVL) analysis is typically helpful in establishing the diagnosis of airway obstruction caused by endobronchial lesions. In this report, we describe a patient with emphysema and tobacco abuse who presented with chronic dry cough and severe chronic obstructive pulmonary disease (COPD) refractory to standard therapy. The initial FVL showed a relatively normal forced expiratory peak flow shape followed by a smooth flattening of the expiratory curve on spirometry, a pattern consistent with distal airway obstruction as seen in severe asthma or COPD. The patient was later found to have a large endotracheal mass. This atypical presentation, along with the unusual FVL, led to a significant delay in the diagnosis of the tracheal mass. A high level of suspicion is needed to diagnose variable intrathoracic airway obstruction in patients presenting with severe asthma or COPD who fail to improve with standard therapy.