Embryology · Respiratory system, diaphragm and body cavities

Congenital pulmonary airway malformation, sequestration and bronchogenic cyst !

Malformation

These are congenital lung masses: cysts or lung tissue that does not work. Many show up on pregnancy ultrasound; others cause infections later.

Updated 2026-11-01

See it in 3D: Left lower lobe · Right lower lobe · Thoracic aorta · Main bronchi · Trachea

What it is

These lesions come from errors in branching of the bronchial tree or from accessory respiratory buds of the foregut. Congenital pulmonary airway malformation (CPAM) is cystic tissue that connects with the airway; sequestration is lung tissue with no bronchial connection, supplied by a systemic artery; a bronchogenic cyst is an isolated bud, usually in the mediastinum. They are told apart by their airway connection and their blood supply.

Embryological cause

CPAM: abnormal growth of terminal bronchioles during branching, with cysts in place of normal alveoli.
Sequestration: an accessory respiratory bud of the foregut, caudal to the normal one, grows without joining the bronchial tree and keeps a systemic artery.
If the accessory bud appears before the pleura forms, it ends up inside the lobe (intralobar); if later, it gets its own pleura (extralobar).
Bronchogenic cyst: abnormal budding of the tracheal or bronchial bud that pinches off as a cyst lined by respiratory epithelium, with cartilage in its wall.

Telling congenital lung masses apart

Lesion	Airway	Blood supply	Typical presentation
CPAM	Connects	Pulmonary artery	Mass on ultrasound; respiratory distress
Intralobar sequestration	No connection	Systemic artery	Recurrent pneumonia
Extralobar sequestration	No connection	Systemic artery	Fetal mass; other anomalies
Bronchogenic cyst	Usually none	Bronchial	Mediastinal mass; compression

How it presents

Many are found on second-trimester ultrasound as an echogenic or cystic lung mass.
Some lesions shrink relative to the fetus as pregnancy goes on, and the newborn has no symptoms.
Large ones shift the mediastinum, cause fetal hydrops and respiratory distress at birth.
In childhood: recurrent pneumonia in the same lobe, haemoptysis or an incidental finding on X-ray.

Diagnosis

Prenatal ultrasound with Doppler: an artery arising from the aorta points to sequestration.
Mass volume ratio (CVR) to estimate the risk of hydrops.
Chest CT angiography after birth to define the lesion and its blood supply.

Test yourself

Think of the answer, then tap the question to see it.

What distinguishes a pulmonary sequestration from a CPAM?

A sequestration does not connect with the bronchial tree and is supplied by a systemic artery; a CPAM connects with the airway and has pulmonary blood supply.

What is the embryological origin of pulmonary sequestration?

An accessory respiratory bud of the foregut that grows without joining the bronchial tree and keeps a systemic artery.

Where is a bronchogenic cyst typically found?

In the mediastinum, near the carina, although it can lie within the lung.

Which prenatal Doppler finding suggests sequestration?

An artery arising from the aorta and running straight to the lung mass.

Add to my cards (4)

See it in 3D

The structures of Durgical's 3D anatomy where it is found.

Aspiration pneumonia and pneumonitis

← All of embryology

Educational content on embryonic development; not a guide to prenatal diagnosis or to medicines in pregnancy and no substitute for a health professional's advice. No doses are given.

Sources: Fetal Lung Mass | Nemours KidsHealth (Nemours KidsHealth, 2024); Langman's Medical Embryology, 13th ed., ch. 14: Respiratory System (Wolters Kluwer, 2015).

Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake

Representative model, for educational purposes only.