🫁 CPAM + CDH Hybrid Lesion

When Lung Mass and Diaphragm Abnormality Overlap

Fetal thoracic lesions are not always clearly categorized.

Occasionally, ultrasound findings suggest features of both:

• CPAM-like lung mass
• Diapagmatic abnormality resembling CDH

This raises the question:

Can CPAM and CDH coexist?

Or is it something else?

1️⃣ What Is a Hybrid Lesion?

In fetal lung pathology, a “hybrid lesion” usually refers to:

👉 A lesion that shows characteristics of CPAM and bronchopulmonary sequestration (BPS).

However, in rare cases, confusion arises when:

• A large CPAM displaces the diaphragm
• Or a CDH mimics a cystic lung lesion
• Or both anomalies truly coexist

True coexistence of CPAM and CDH is rare —

but diagnostic overlap can occur.

2️⃣ Why Can CPAM Mimic CDH?

A large CPAM may:

• Cause mediastinal shift
• Compress the diaphragm
• Distort thoracic anatomy

In severe cases, the diaphragm may appear poorly visualized.

If the stomach is displaced superiorly,

it can resemble herniation.

But key distinction:

👉 In CPAM, abdominal organs do NOT truly pass through a diaphragmatic defect.

3️⃣ Why Can CDH Mimic CPAM?

In CDH:

• Herniated bowel loops may appear cystic.
• Fluid-filled bowel can look like macrocystic CPAM.
• The mass may look intrapulmonary at first glance.

This is why:

Stomach and liver position must always be checked carefully.

4️⃣ When to Suspect True Combined Pathology?

Very rare, but consider further evaluation if:

• Clear diaphragmatic discontinuity
• True abdominal organ herniation
• AND a separate intrapulmonary cystic lesion

In such cases:

• Detailed fetal MRI is helpful
• Multidisciplinary counseling required

5️⃣ Imaging Strategy in Suspected Hybrid Cases

If findings are unclear:

1. Reassess stomach position
2. Confirm diaphragm continuity
3. Use color Doppler
4. Evaluate for feeding artery
5. Consider fetal MRI

MRI is particularly useful when anatomy is distorted.

🔑 Clinical Insight

Most “hybrid” suspicions are actually:

• CPAM with significant mass effect
  or
• CDH with cystic-appearing bowel

True dual pathology is rare.

Careful systematic evaluation prevents misdiagnosis.

🧠 Key Takeaway

When evaluating a fetal thoracic mass:

Always determine whether the abnormality arises from lung tissue

or represents herniated abdominal content.

That distinction defines prognosis and management.