Congenital pulmonary airway malformations (CPAM)
The term CPAM (Congenital Pulmonary Airway Malformations) replaced the outdated term CCAM, since only one variant of the anomaly is truly adenomatoid. The condition is associated with impaired airway development in early stages. Blood supply comes from the pulmonary artery, and venous drainage occurs via the pulmonary veins.
According to the modified Stocker classification, several types are distinguished:
- Type 0: Incompatible with life.
- Type 1: The most frequent (>65%). Multiple large communicating cysts (up to 10 cm). Causes mediastinal shift.
- Type 2: Small cysts up to 2 cm. Frequently associated with other malformations.
- Type 3: Solid mass with microcysts (<5 mm), poor prognosis.
- Type 4: Large cysts, difficult to distinguish from Type 1, but their association with malignant pleuropulmonary blastoma (PPB) is debated. The presence of DICER1 gene mutations is a reason to suspect PPB.
Pulmonary sequestration
Pulmonary sequestration is a segment of lung tissue that does not communicate with the normal bronchial tree and receives systemic arterial blood supply (usually from the aorta). Two main types are distinguished, which are well differentiated on MDCT (MDCT).
| Sign | Intralobar (ILS) | Extralobar (ELS) |
|---|---|---|
| Frequency | ~75% of cases | ~25% of cases |
| Pleura | Shared with the normal lung | Own pleural covering |
| Venous drainage | Into the pulmonary venous system | Into systemic veins (e.g., v. azygos) |
| Localization | More commonly left lower lobe | Left basal (sometimes subdiaphragmatic) |
| Association with malformations | Rarely | Frequent (in 65% of cases) |
Bronchogenic cysts and lobar overinflation
Bronchogenic cysts are usually located in the lower lobes or the subcarinal zone of the mediastinum. Their walls are lined with bronchial epithelium. In subcarinal localization, a large cyst can elevate the left main bronchus and cause compression (stridor, wheezing). On MRI, cysts demonstrate high (hyperintense) signal on T2-weighted images, and the presence of air inside indicates a fistula or infection.
Congenital lobar overinflation develops due to a check-valve mechanism in an abnormal bronchus. During inspiration, air enters the lobe, but is blocked during expiration. On the radiograph, the affected lobe (usually the left upper) appears expanded, hyperlucent (with attenuated vascular pattern) and displaces the mediastinum.
Pulmonary hypoplasia and scimitar syndrome
Pulmonary hypoplasia can be primary or secondary. The secondary form often arises from intrauterine compression, for example, in congenital Bochdalek hernia (usually on the left). Imaging reveals diffuse opacification of the hemithorax with mediastinal shift toward the lesion.
A specific variant of combined pathology is congenital venolobar syndrome (scimitar syndrome). It includes right lung hypoplasia and anomalous systemic venous drainage. The pulmonary vein drains into the inferior vena cava, forming a left-to-right shunt. On the radiograph, this vein resembles a curved Turkish sword (scimitar).
Briefly: answers to topical questions
What changes occur in the lungs in Macleod syndrome?
Swyer-James-Macleod syndrome features changes characteristic of post-infectious bronchiolitis obliterans.
- Bronchiolitis obliterans (bronchiolitis obliterans) — sharply demarcated focal areas of increased and decreased lung tissue density, bronchial wall thickening, and bronchiectasis.
- Areas of increased lucency (lucent lung regions) — zones showing a decrease in vessel caliber.
- Air-trapping (air-trapping) — areas of increased transparency (poorly ventilated and perfused zones) frequently visualized on expiratory CT.
Distinguishing sequestrations: INTRAlobar — "within the system" (shared pleura, normal drainage into pulmonary veins). EXTRAlobar — "outside the system" (own pleura, drainage into systemic veins).
Class and exam questions
How to distinguish type 1 CPAM from pleuropulmonary blastoma (PPB) on CT?
In CPAM, the septa between large cysts are thin and do not enhance with contrast. PPB is characterized by multilocular cysts with thicker, nodular septa, as well as a frequent association with pneumothorax.
In which direction does the mediastinum shift in pulmonary aplasia or hypoplasia?
The mediastinum shifts toward the lesion due to reduced lung volume, while the healthy lung undergoes compensatory hyperinflation.
What is the essence of the "left pulmonary artery sling" anomaly?
In this malformation, the left pulmonary artery arises from the right and loops posteriorly around the tracheal bifurcation. This is often accompanied by right main bronchus stenosis and right lung hyperinflation.
What else to study on this topic
- Radiological differential diagnosis of anterior, middle, and posterior mediastinal masses in children.
- Fetal MRI: role in assessing pulmonary hypoplasia in Bochdalek hernias.
- Bronchial atresia: segmental hyperlucency on CT (minIP).
- Causes of secondary pulmonary hypoplasia (Potter sequence, Jeune syndrome).
Master the entire topic in the "Diagnostic Radiology" course
This is a summary. The course covers everything tested in classes and exams.
- Complete study guide on "Congenital pulmonary malformations" and 2,199 more pages of the subject
- Assignments and quizzes after every topic — just like in a colloquium
- AI tutor answers questions on the topic anytime
- 10 video lessons on the subject
Other Topics in "Pediatric Diagnostic Radiology"
Prepared by WhiteCoat Pro faculty in accordance with the medical school curriculum. For educational purposes only.