Paper II
Question
Define bronchiectasis. Add a note on its etiopathogenesis, morphological features and complications.
Answer
Definition
- Bronchiectasis is the permanent, abnormal dilatation of bronchi and bronchioles, caused by chronic destruction of the bronchial wall (muscle and elastic tissue), usually resulting from persistent or severe infection combined with airway obstruction
Etiopathogenesis
- Requires two key components acting together: obstruction and chronic/recurrent infection
- Obstruction (e.g., tumour, foreign body, mucus plugging in cystic fibrosis) impairs normal mucociliary clearance, allowing secretions to accumulate distally
- Persistent infection in the stagnant secretions causes ongoing inflammatory destruction of the bronchial wall (muscle, elastic tissue, cartilage), weakening it
- The weakened wall, combined with traction from surrounding fibrosis and the pressure of retained secretions, causes progressive, irreversible dilatation
- Underlying causes: Cystic fibrosis (most common cause in developed countries — abnormal mucus clearance), post-infectious (severe pneumonia, tuberculosis), bronchial obstruction (tumour, foreign body), immunodeficiency states (recurrent infections), primary ciliary dyskinesia (impaired mucociliary clearance), allergic bronchopulmonary aspergillosis
Morphological features
Gross
- Airways dilated up to 4x normal diameter, extending to the lung periphery (unlike normal tapering)
- Most severe in the lower lobes, particularly the more vertical/dependent airways
- Dilated bronchi may be visible almost to the pleural surface
Microscopic
- Intense acute and chronic inflammatory infiltrate within the bronchial/bronchiolar walls
- Desquamation of lining epithelium, with extensive areas of ulceration
- Squamous metaplasia of the remaining epithelium
- Fibrosis of the bronchial wall in more chronic cases, sometimes with obliteration of the bronchiolar lumen
Complications
- Recurrent, chronic pulmonary infections
- Haemoptysis (sometimes massive, from erosion of bronchial vessels)
- Cor pulmonale (secondary pulmonary hypertension from chronic hypoxia)
- Metastatic brain abscess (from haematogenous spread of infection)
- Secondary (AA) amyloidosis (from chronic suppurative inflammation)