What is CPAM?
CPAM is a congenital lung malformation characterized by abnormal proliferation of terminal bronchioles forming cystic or solid lung masses.
It was previously called CCAM (Congenital Cystic Adenomatoid Malformation).
๐ When is CPAM suspected on ultrasound?
Most commonly detected in the mid-trimester scan (18โ24 weeks).
Typical findings:
- Echogenic lung mass
- Cystic or mixed echogenic lesion
- Mediastinal shift
- Possible polyhydramnios (if severe)
Sometimes it looks like:
A bright area in one lung that should not be there.
๐ Types of CPAM (Simplified for Ultrasound)
1๏ธโฃ Macrocystic CPAM
- Large visible cysts (>5 mm)
- Clear cystic spaces
- Usually easier to diagnose
2๏ธโฃ Microcystic CPAM
- Solid-appearing echogenic mass
- No obvious cysts
- Can mimic other lung lesions
๐จ When does CPAM become concerning?
CPAM is not dangerous by default.
Concern increases when:
- Rapid growth
- Mediastinal shift
- Cardiac compression
- Hydrops develops
The most important predictor:
๐ CVR (CPAM Volume Ratio)
CVR > 1.6 is associated with higher risk of hydrops.
๐ก What is CVR?
CVR = (Length ร Width ร Height ร 0.52) / Head circumference
Used to estimate risk of fetal compromise.
๐ Natural Course
Many CPAM lesions:
- Grow until around 26โ28 weeks
- Then stabilize or regress
- Some almost disappear in late pregnancy
Regression does NOT mean the lesion is gone after birth.
๐ง CPAM vs Bronchopulmonary Sequestration (BPS)
Key difference:
| CPAM | BPS |
| No systemic feeding artery | Has systemic feeding artery |
| Pulmonary circulation | Systemic arterial supply (from aorta) |
Always use color Doppler to check for a feeding vessel.
๐ถ After Birth
Most infants do well.
However:
- Some require surgical resection
- Even asymptomatic lesions may be removed later
- Infection risk exists
๐ The Key Clinical Thinking
When you see a lung mass:
- Is it cystic or solid?
- Is there a feeding artery?
- Is there mediastinal shift?
- Is hydrops developing?
- What is the CVR?
CPAM evaluation is about progression, not just detection.
