Bronchiectasis
- Lesion
Bronchiectasis is permanent widening of bronchi after their muscle and elastic tissue are destroyed by chronic infection, often behind poor mucus clearance.
What it is
Bronchiectasis is permanent dilation of bronchi and bronchioles caused by inflammatory destruction of smooth muscle and elastic tissue. Two forces act together: obstruction or poor clearance lets secretions pool, and persistent infection damages the wall. It complicates cystic fibrosis, primary ciliary dyskinesia, immune deficiency, severe necrotising pneumonia, obstruction by tumour or foreign body, ABPA and autoimmune disease; many cases remain idiopathic.
Structure
- Gross: dilated bronchi up to several times normal width, cylindrical, fusiform or saccular, full of mucopurulent secretions; cut surface looks cystic.
- Active disease: intense acute and chronic inflammation in the wall, epithelial ulceration and desquamation, sometimes abscess.
- Squamous metaplasia of the remaining epithelium further weakens clearance.
- Chronic disease: peribronchial fibrosis and obliteration of smaller bronchioles (bronchiolitis obliterans).
Step by step
- A defect in clearance (thick CF mucus, immotile cilia) or a block (tumour, foreign body, mucus plug) lets secretions pool.
- Bacteria colonise the stagnant mucus and cause chronic infection.
- Neutrophils release proteases and oxidants that destroy smooth muscle, elastic tissue and cartilage support.
- The weakened wall is pulled outward by the surrounding lung and dilates permanently.
- Dilated, scarred airways clear mucus even less well: the cycle of infection and damage continues.
- Small distal bronchioles are obliterated by fibrosis.
Causes of bronchiectasis
| Group | Examples | Why |
|---|---|---|
| Hereditary clearance defects | Cystic fibrosis, primary ciliary dyskinesia (Kartagener) | Thick mucus or immotile cilia |
| Immune defects | Hypogammaglobulinaemia and other immunodeficiencies | Repeated bacterial infection |
| After severe infection | Necrotising bacterial, viral (measles, pertussis) or fungal pneumonia, tuberculosis | Wall destroyed in one episode |
| Obstruction | Tumour, foreign body, mucus impaction | Localised pooling behind the block |
| Immune and allergic | ABPA, rheumatoid arthritis, SLE, IBD, chronic lung rejection | Inflammation of the airway wall |
Clinical notes
- Cough worst on rising in the morning as pooled pus drains; dyspnoea, clubbing, hemoptysis.
- Old complications (less frequent with antibiotics): cor pulmonale, brain abscess, AA amyloidosis.
- Think CF in a young patient, Kartagener with dextrocardia, ABPA in an asthmatic with eosinophilia and high IgE.
Test yourself
Think of the answer, then tap the question to see it.
What two processes together cause bronchiectasis?
Obstruction or impaired clearance that lets secretions pool, and persistent infection whose inflammation destroys the bronchial wall.
What is the defect in Kartagener syndrome and what does it cause?
Primary ciliary dyskinesia from defective ciliary motor proteins such as dynein: bronchiectasis, sinusitis, situs inversus and male infertility.
Which bacteria are most often cultured from bronchiectatic sputum?
Haemophilus influenzae most often, then Pseudomonas aeruginosa.
Elsewhere in DurgiPedia
Connections
Microorganisms1
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Bronchiectasis (StatPearls (NCBI Bookshelf), 2025); Primary ciliary dyskinesia: MedlinePlus Genetics (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.