Bronchiectasis is relatively uncommon in the United States; however, bronchiectasis associated with cystic fibrosis occurs with a prevalence of 1 in 2,500 white births. Native Americans in Alaska have fourfold higher incidence of bronchiectasis than the general population.

The different forms of bronchiectasis may occur separately or simultaneously. In cylindrical bronchiectasis, the bronchi expand unevenly, with little change in diameter, and end suddenly in a squared-off fashion. In varicose bronchiectasis, abnormal, irregular dilation and narrowing of the bronchi give the appearance of varicose veins. In saccular bronchiectasis, many large dilations end in sacs. These sacs balloon into pus-filled cavities as they approach the periphery and are then called saccules. (See Forms of bronchiectasis.)

This disease results from conditions associated with repeated damage to bronchial walls and abnormal mucociliary clearance, which cause a breakdown of supporting tissue adjacent to airways. Such conditions include cystic fibrosis; immunologic disorders (agammaglobulinemia, for example); recurrent, inadequately treated bacterial respiratory tract infections, such as tuberculosis; and complications of measles, pneumonia, pertussis, or influenza. Bronchiectasis is also due to obstruction (by a foreign body—most common in children, tumor, or stenosis) in association with recurrent infection, as well as inhalation of corrosive gas or repeated aspiration of gastric juices into the lungs. Congenital anomalies are relatively uncommon causes, such as bronchomalacia, congenital bronchiectasis, immotile cilia syndrome, and Kartagener’s syndrome, a variant of immotile cilia syndrome characterized by situs inversus, bronchiectasis, and either nasal polyps or sinusitis.

In bronchiectasis, hyperplastic squamous epithelium denuded of
cilia replaces ulcerated columnar epithelium. Abscess formation involving all layers of the bronchial wall produces inflammatory cells and fibrous tissue, resulting in dilation and narrowing of the airways. Mucus plugs or fibrous tissue obliterates smaller bronchioles, whereas peribronchial lymphoid tissue becomes hyperplastic. Extensive vascular proliferation of bronchial circulation occurs and produces frequent hemoptysis.