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).
π When is CPAM suspected on ultrasound?
Most commonly detected in the mid-trimester scan (18β24 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.
π Types of CPAM (Simplified for Ultrasound)
1οΈβ£ Macrocystic CPAM
- Large visible cysts (>5 mm)
- Clear cystic spaces
- Usually easier to diagnose
2οΈβ£ Microcystic CPAM
- Solid-appearing echogenic mass
- No obvious cysts
- Can mimic other lung lesions
π¨ 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:
π CVR (CPAM Volume Ratio)
CVR > 1.6 is associated with higher risk of hydrops.
π‘ What is CVR?
CVR = (Length Γ Width Γ Height Γ 0.52) / Head circumference
Used to estimate risk of fetal compromise.
π Natural Course
Many CPAM lesions:
- Grow until around 26β28 weeks
- Then stabilize or regress
- Some almost disappear in late pregnancy
Regression does NOT mean the lesion is gone after birth.
π§ 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.
πΆ After Birth
Most infants do well.
However:
- Some require surgical resection
- Even asymptomatic lesions may be removed later
- Infection risk exists
π 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.