Congenital lung anomalies
- Lesion
Rare birth defects of the lung: too little lung, cysts left over from the foregut, or a piece of lung cut off from the airway with its own artery.
What it is
The lung grows as a bud from the ventral foregut, so faults in budding, branching or blood supply leave recognisable lesions. Pulmonary hypoplasia (small lungs) follows anything that squeezes the chest or removes amniotic fluid in fetal life. Foregut cysts, sequestrations and congenital pulmonary airway malformations are the masses a pathologist sees in infants and children.
Structure
- Hypoplasia: small, light lungs with fewer and simpler airways and alveoli for the gestational age.
- Bronchogenic cyst: thin-walled cyst full of mucus, lined by pseudostratified ciliated columnar epithelium, with cartilage plates and bronchial glands in the wall.
- Sequestration: a wedge of disorganised lung with dilated airspaces, inflammation and fibrosis, supplied by a thick systemic artery.
- CPAM: back-to-back cysts of varying size lined by bronchiolar-type epithelium, without cartilage in most types.
Step by step
- The lung bud branches from the foregut and needs space, fluid and fetal breathing movements to grow.
- A hernia or lack of amniotic fluid takes away that space or stretch, so the airways stop branching early: hypoplasia.
- A piece of foregut that pinches off and stays separate grows into a closed cyst (bronchogenic, oesophageal or enteric).
- An accessory lung bud that keeps a systemic artery and never joins the bronchial tree becomes a sequestration.
- Trapped secretions in a sequestration or cyst become infected, which is how many of them come to attention.
Sequestration: extralobar vs intralobar
| Feature | Extralobar | Intralobar |
|---|---|---|
| Pleura | Own pleural covering, outside the lung | Inside the visceral pleura of a lobe |
| Usual age | Infants, often with other anomalies | Older children and adults |
| How it presents | Mass lesion | Recurrent localised infection, bronchiectasis |
| Blood supply | Systemic artery from the aorta | Systemic artery from the aorta |
Clinical notes
- Newborn with diaphragmatic hernia or Potter sequence: respiratory failure from hypoplasia.
- Bronchogenic cysts are often found by chance; they show up when they compress an airway or become infected.
- Intralobar sequestration in the left lower lobe of a child with repeated pneumonia is the classic case; the surgeon must find the aortic branch before resection.
Test yourself
Think of the answer, then tap the question to see it.
Which two fetal situations classically cause pulmonary hypoplasia?
Congenital diaphragmatic hernia, which takes up chest space, and oligohydramnios (for example renal agenesis), which removes the fluid the lungs need to grow.
What features in the wall identify a bronchogenic cyst?
A lining of ciliated pseudostratified columnar epithelium with cartilage, bronchial glands and smooth muscle: it copies a normal bronchus.
What two features define a pulmonary sequestration?
No connection to the airways and an abnormal arterial supply from the aorta or one of its branches.
Elsewhere in DurgiPedia
- Pulmonary hypoplasia
- Congenital pulmonary airway malformation, sequestration and bronchogenic cyst
- Esophageal atresia and tracheoesophageal fistula
- Lung development: the five stages
Connections
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: Lung Diseases (MedlinePlus, US National Library of Medicine, 2025).
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Representative model, for educational purposes only.