Beyond bronchitis: a review of the congenital and acquired abnormalities of the bronchus.

Anomalies of the bronchus can be both congenital and acquired. Several different congenital aberrations of the bronchial anatomy are commonly encountered including tracheal bronchus, accessory cardiac bronchus, and bronchial agenesis/aplasia/hypoplasia. In addition, Williams-Campbell syndrome and cystic fibrosis are two other congenital conditions that result in bronchial pathology. Acquired pathology affecting the bronchi can typically be divided into three broad categories of bronchial disease: bronchial wall thickening, dilatation/bronchiectasis, and obstruction/stenosis. Bronchial wall thickening is the common final response of the airways to irritants, which cause the bronchi to become swollen and inflamed. Bronchiectasis/bronchial dilatation can develop in response to many aetiologies, including acquired conditions such as infection, pulmonary fibrosis, recurrent or chronic aspiration, as well as because of congenital conditions such as cystic fibrosis. The causes of obstruction and stenosis are varied and include foreign body aspiration, acute aspiration, tracheobronchomalacia, excessive dynamic airway collapse, neoplasm, granulomatous disease, broncholithiasis, and asthma. Knowledge of normal bronchial anatomy and its congenital variants is essential for any practicing radiologist. It is the role of the radiologist to identify common imaging patterns associated with the various categories of bronchial disease and provide the ordering clinician a useful differential diagnosis tailored to the patient's clinical history and imaging findings. Teaching Points • Bronchial disorders are both congenital and acquired in aetiology.• Bronchial disease can be divided by imaging appearance: wall thickening, dilatation, or obstruction.• Bronchial wall thickening is the common final response of the airways to irritants.• Imaging patterns must be recognised and the differential diagnosis tailored for patient management.