Common Causes of Bronchiectasis
The common causes of bronchiectasis from the listed options are: pneumonia (b), cystic fibrosis (c), and tuberculosis (e). Bronchogenic carcinoma and asbestosis are not typical causes of bronchiectasis.
Evidence-Based Analysis of Each Option
Pneumonia (b) - COMMON CAUSE ✓
- Bacterial pneumonia is a well-established cause of bronchiectasis, particularly when occurring in childhood, resulting in permanent bronchial wall damage 1.
- Post-infectious bronchiectasis from severe pneumonia represents a significant proportion of cases, with focal damage leading to localized bronchiectasis 2, 3.
- The mechanism involves acute infection causing destruction of elastic and muscular components of bronchial walls, with subsequent permanent airway dilation 1.
Cystic Fibrosis (c) - COMMON CAUSE ✓
- Cystic fibrosis is probably the most common identifiable cause of bronchiectasis in the United States and Europe, occurring in 1 per 2,000 to 3,000 live births 1.
- CF accounts for 3-4% of adult patients presenting with bronchiectasis 1.
- The pathophysiology involves mutation of the CF transmembrane regulator protein, leading to excessive tenacious mucus secretion, impaired mucus transport, and proximal airway plugging with subsequent bronchiectasis 1, 2.
Tuberculosis (e) - COMMON CAUSE ✓
- Healed tuberculosis is a recognized cause of bronchiectasis, particularly through traction mechanisms 1.
- In patients with healed TB, traction on major airways from surrounding fibrotic lung parenchyma distorts airway architecture, leading to recurrent infection and traction bronchiectasis 1.
- Post-tuberculous bronchiectasis remains an important cause globally, particularly in endemic regions 2, 4.
Bronchogenic Carcinoma (a) - NOT A COMMON CAUSE ✗
- While bronchial obstruction from tumors can theoretically cause focal bronchiectasis 1, 2, bronchogenic carcinoma is not listed as a common cause in major guidelines.
- The mechanism would be through bronchial obstruction leading to distal infection and airway damage, but this represents a rare scenario 1.
Asbestosis (d) - NOT A COMMON CAUSE ✗
- Asbestosis is not mentioned in any of the guideline evidence as a cause of bronchiectasis 1.
- While other fibrosing lung diseases (sarcoidosis, idiopathic pulmonary fibrosis) can cause traction bronchiectasis 1, asbestosis is not specifically identified as a common cause.
Clinical Context
A systematic search for underlying causes should be performed in all bronchiectasis patients, as one or more causative factors can be identified in 47% of cases, with important prognostic or therapeutic significance in 15% 1.
The most common identifiable causes overall include:
- Cystic fibrosis (most common in developed countries) 1
- Post-infectious damage (pneumonia, pertussis, measles, tuberculosis) 1
- Immunodeficiency states (hypogammaglobulinemia found in 7% of cases) 1, 2
- Allergic bronchopulmonary aspergillosis (4% of cases) 1, 2
- Primary ciliary dyskinesia (≤5% of cases) 1, 2
Answer: b, c, and e are correct.