Pathogenesis and morphology of congenital lung cysts
The development of congenital lung cysts is based on impaired embryonic differentiation, in which individual tissue fragments detach from the primitive gut. Pathological cavities formed in this manner become isolated within the thoracic cavity.
The most common form of anomaly is bronchogenic cysts. The main morphological feature of this form is that the inner wall of the cavity is lined with bronchial epithelium.
The course of cystic malformations is often complicated by secondary pathological processes. In clinical and anatomical practice, the following main complications are distinguished:
- Purulent inflammation with the development of intrapulmonary abscesses;
- Destructive changes in tissue leading to rupture of contents;
- Development of severe conditions such as pyothorax (accumulation of pus in the pleural cavity), pneumothorax (accumulation of air), and pulmonary hemorrhage;
- Formation of hemothorax and collapse of lung tissue — atelectasis.
Essence of bronchopulmonary sequestration
Bronchopulmonary sequestration is a developmental malformation consisting in the formation of an isolated pulmonary segment. The main sign of this anomaly is that the formed area is not connected to the normal bronchial tree and pulmonary artery system.
Due to complete separation from the pulmonary circulation, the arterial blood supply to the sequestered tissue occurs via an anomalous pathway — directly from the systemic circulation, i.e., from the aorta or its major branches.
Classification and forms of sequestration
Depending on the location of the sequestered fragment relative to the organ parenchyma, two clinical and anatomical forms of the pathology are distinguished:
- Extralobar sequestration:
- Localization: the pathological focus is located outside the lung tissue — in the mediastinum;
- Age group: detected in newborns;
- Features: often combined with other congenital malformations.
- Intralobar sequestration:
- Localization: the defective segment is located directly inside the pulmonary parenchyma;
- Age group: characteristic of adults;
- Manifestations: clinically expressed as recurrent infectious complications.
Comparative characteristics of sequestration variants
To quickly differentiate between the two types of bronchopulmonary sequestration, the following systematization is used:
| Criterion | Extralobar sequestration | Intralobar sequestration |
|---|---|---|
| Localization | In the mediastinum | Within the pulmonary parenchyma |
| Age of detection | Neonates | Adults |
| Associated changes | Combined with other malformations | Recurrent infectious complications |
| Blood supply | From the aorta or its branches | From the aorta or its branches |
EXTRA-MEDIASTINUM (Extralobar — in the mediastinum, in newborns), INTRA-PARENCHYMA (Intralobar — in the parenchyma, in adults with infectious complications).
Class and exam questions
From which structures during embryogenesis do congenital lung cysts develop?
Congenital lung cysts form as a result of the separation of tissue fragments from the primitive gut during embryogenesis. Common bronchogenic cysts are lined on the inside with bronchial epithelium.
Where does the blood supply to the sequestered lung area come from?
The sequestered segment is not connected to the pulmonary artery. Its blood supply comes from arterial blood flowing directly from the aorta or its branches.
What complications can arise from the destruction of congenital lung cysts?
Complications include purulent inflammation (abscesses), and upon destruction — pyothorax, pneumothorax, pulmonary hemorrhage, as well as hemothorax and atelectasis.
What are the main differences between extralobar and intralobar sequestration?
The extralobar form is localized in the mediastinum, detected in newborns, and combined with other malformations. The intralobar form is located inside the lung parenchyma, is characteristic of adults, and manifests as recurrent infectious complications.
What else to study on this topic
- Molecular and embryonic mechanisms of primitive gut fragment detachment during cyst formation
- Features of the histological structure of the bronchial epithelium in the wall of a bronchogenic cyst
- Pathomorphology of destructive processes in the cyst: mechanisms of development of pyothorax and pneumothorax
- Anatomic variants of anomalous blood supply to sequestrations from branches of the aorta
- The clinical course of recurrent infectious complications in intralobar sequestration
- The spectrum of associated congenital malformations in extralobar sequestration in newborns
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