Variations of the tracheobronchial tree: anatomical and clinical significance.

Tracheobronchial variations can be found during routine bronchoscopy or computed tomography. Previous sources estimate an incidence of 1-12%; however, these variations are often asymptomatic. Symptomatic patients present typically with cough and lower respiratory tract infection. Knowledge and understanding of tracheobronchial variations have important implications for diagnosis of symptomatic patients and performing certain procedures, including bronchoscopy and endotracheal intubation. In this review, we describe the most commonly encountered variations, tracheal bronchus and accessory cardiac bronchus, along with three minor abnormalities of this region. We also review the various imaging modalities in the diagnosis and treatment of these conditions.