Aetiology

A number of underlying conditions may be responsible for the development of bronchiectasis. In 50% of adults and 25% of children it is idiopathic (1).

Focal bronchiectasis may be caused by:

• Bronchial obstruction – foreign body, broncholith, a slowly growing tumor, anatomic distortion following lobectomy, enlarged lymph node
• severe case of respiratory infection (2).

Diffuse bronchiectasis may be caused by:

• cystic fibrosis
• primary ciliary dyskinesia
• allergic bronchopulmonary aspergillosis (ABPA)
• aspiration or toxic inhalation
• inflammatory disorders - rheumatoid arthritis, inflammatory bowel disease
• decreased host immunity - hypogammaglobulinaemia, HIV infection
• congenital disorders - alpha-1 antitrypsin deficiency, Marfan's syndrome, Young's syndrome (2).

The causes of bronchiectasis may be classified into five main groups:

• defective host defenses
• localised bronchial obstruction
• post-infectious
• inflammatory disorders
• miscellaneous.

British Thoracic Society recommends that the underlying cause of bronchiectasis should be assessed in all patients (3).

Reference:

1. ten Hacken NH, van der Molen T. Bronchiectasis. BMJ. 2010 Jul 14;341:c2766. doi: 10.1136/bmj.c2766. PMID: 20630967.
2. Rosen MJ. Chronic cough due to bronchiectasis: ACCP evidence-based clinical practice guidelines. Chest. 2006;129(1 Suppl):122S-131S
3. Pasteur MC et al. British Thoracic Society guideline for non-CF bronchiectasis. Thorax. 2010;65 Suppl 1:i1-58