RESPIRATORY · CONGENITAL
Congenital lung malformations
Rare congenital lung lesions, sorted by two questions: does it connect to the airway, and where does its blood come from?
HOW THEY ARISE
Errors of lung budding
Most congenital lung malformations are errors of early foregut and lung-bud development in the first trimester - abnormal budding, branching or airway formation. Where in that process the error occurs explains the airway connection and blood supply that go on to define each lesion.
HOW TO THINK ABOUT THEM
Two questions sort most lesions
Congenital lung malformations are rare and often found on antenatal scans. Faced with one, two questions get you most of the way: does it connect to the airway? and where does its blood supply come from? Those two answers separate the big players - CPAM from sequestration - and guide everything else.
Airway connection?
- CPAM communicates with the tracheobronchial tree (can air-trap and get infected)
- Sequestration does not connect to the airway
- Bronchogenic cyst may or may not connect (foregut origin)
Blood supply?
- CPAM is supplied by the pulmonary circulation
- Sequestration is supplied by a systemic artery, often straight off the aorta - the finding that clinches it on imaging
| Feature | CPAM | Sequestration |
|---|---|---|
| Airway connection | Yes - communicates with tracheobronchial tree | No airway communication |
| Blood supply | Pulmonary circulation | Systemic artery (often from aorta) |
| Nature | Cystic / adenomatous malformation of terminal bronchioles | Non-functioning lung tissue |
| Presentation | Antenatal mass, neonatal distress, later recurrent pneumonia | Antenatal mass, hydrops, later recurrent infection |
| Key investigation | Define the cysts (CT) | Identify the systemic feeding artery |
CPAM
Congenital pulmonary airway malformation
Formerly "CCAM" (congenital cystic adenomatoid malformation). A branching abnormality producing cystic/adenomatous overgrowth of terminal bronchioles, usually confined to one lobe (~1 in 11,000-30,000 births). Large lesions cause mass effect and mediastinal shift at birth; small ones surface later as recurrent pneumonia.
| Type | Features | Prognosis |
|---|---|---|
| Type 0 | Acinar dysplasia; all lobes involved; very rare | Lethal |
| Type 1 | Most common; one or a few large cysts | Best prognosis |
| Type 2 | Multiple small cysts; often other anomalies | Depends on associated anomalies |
| Type 3 | Large solid/homogeneous mass; mediastinal shift | Poor if large (hypoplasia / PPHN) |
| Type 4 | Large peripheral cysts; rare (link with pleuropulmonary blastoma) | Generally good if resectable |
SEQUESTRATION
Bronchopulmonary sequestration
Non-functioning lung tissue with no airway connection and a systemic arterial supply. The split is intralobar vs extralobar.
| Intralobar | Extralobar | |
|---|---|---|
| Frequency | More common | Less common |
| Pleura | Within normal lobe, no separate pleura | Own visceral pleura |
| Presents | Older child / adult, recurrent pneumonia | Fetal / neonatal period, respiratory distress |
| Associated anomalies | Less common | More common |
| Typical site | Lower lobes, left > right | Often left, can be below the diaphragm |
THE REST, IN BRIEF
Other congenital lung lesions
Congenital lobar emphysema
- Ball-valve air trapping overdistends a lobe
- Left upper lobe most common; then RML, RUL
- CXR: hyperinflated lobe, mediastinal shift (may look opaque early before fluid clears)
- Lobectomy if severe; some settle
Bronchogenic cyst
- Anomalous foregut budding
- Usually posterior to the trachea
- Often quiet until later (cough, wheeze, infection)
- Usually excised - infection and rare malignant change
Pulmonary lymphangiectasia
- Dilated pulmonary lymphatics
- Links: T21, Noonan, Turner; or secondary (HLHS, infection)
- Early distress, pleural effusions
- High mortality in severe primary disease
Pulmonary hypoplasia
- Small lungs: few alveoli, airways and vessels
- Compression (CDH, mass, effusion) or oligohydramnios (Potter)
- Distress, cyanosis, PPHN
- Ventilate with minimal pressures; outcome depends on cause
Alveolar capillary dysplasia
- Maldeveloped capillaries + misaligned pulmonary veins
- Severe, refractory PPHN in a term-ish baby
- Unresponsive to usual therapy; usually fatal
- Diagnosis often on biopsy / FOXF1
The reflex checks
- Echo for PPHN and cardiac disease
- CT to define the lesion and its blood supply
- Karyotype/microarray if syndromic features
- First exclude the common causes of neonatal lung disease
- Monitor respiratory status; minimal handling for large lesions with mass effect.
- Thermoregulation; assist with imaging and pre-operative preparation.
- Watch for respiratory distress from mass effect, or later infection.
- Support and update the family.
HIGH-YIELD
CPAM vs sequestration vs CDH
| Feature | CPAM | Sequestration | CDH |
|---|---|---|---|
| Core problem | Cystic lung lesion | Non-functioning lung, systemic supply | Abdominal viscera in the chest |
| Airway connection | Yes | No | n/a |
| Blood supply | Pulmonary | Systemic artery | n/a |
| Abdomen / bowel sounds | Normal; chest quiet | Normal | Scaphoid; bowel sounds in chest |
| Main issue | Mass effect +/- hydrops | Usually well; recurrent infection | Pulmonary hypoplasia + PPHN |
| First move | Support; selective intubation if large | Define feeding artery; plan resection | Intubate, NG decompress, no bag-mask |
The whole topic on two axes: airway connection and blood supply. CPAM = connects to the airway, pulmonary supply. Sequestration = no airway connection, systemic arterial supply. Everything else - lobar emphysema, bronchogenic cyst, lymphangiectasia, hypoplasia, ACD - hangs off the same anatomy and physiology.
Educational summary for clinical teaching. Surgical timing and approach are centre-specific.