الفهرس 
EMBRYOLOGY OF THE LUNGSOnly 14 pages are availabe for public view
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Abstract
Congenital cysts of the lung, although rare, vary widely in their presentation and severity. However, frequently they present with dramatic symptoms resulting in the need for prompt diagnosis and treatment.
Pulmonary sequestration, congenital cystic adenomatoid malformation, congenital lobar emphysema, and bronchogenic cysts are congenital lesions that may present as abnormal cystic areas within the pleural cavity in early life.
The classification of congenital pulmonary cysts is much detracted due to controversies arising over the embryology, pathology, nomenclature and aetiology of the different varieties of cysts.
Bronchogenic cysts develop from an abnormal budding of the ventral foregut between the 26th and 40th week of gestation. They are usually located along the trachea and the mainstem bronchi, commonly in the subcarinal region. They are often firmly attached to the airways but rarely communicate with them.
Congenital cystic adenomatoid malformation is a developmental hamartomatous abnormality of the lung with adenomatoid proliferation of cysts resembling bronchioles that is believed to result from focal arrest in fetal lung development before the seventh week of gestation.
A pulmonary sequestration is a mass of nonfunctioning ectopic pulmonary tissue with its own blood supply that arises from the systemic arteries, usually the thoracic and abdominal aorta. An entire lung may be sequestered, in which case the lung is hypoplastic and has no bronchial connection.
Lobar emphysema is overinflation or severe distention of one lobe with compression atelectasis of adjacent lobes, shift of the mediastinum, and herniation of the lung across the midline. This overinflation is usually due to air trapping by a ball-valve mechanism.
Patients present with either progressive respiratory distress or recurrent pulmonary infections, and cystic changes noted on chest roentgenograms. The differentiation of these congenital lesions from resolvable inflammatory cysts is important.
Diagnosis is aided by selective utilization of chest x-ray, ultrasonography, computed tomography and arteriography.
As regard the treatment, any cyst that is enlarging on serial chest film ought to be resected due to the expected respiratory compromise that will occur, and the possibility of infection or malignant transformation to occur in the cyst or in the adjacent compressed lung tissue.
Fetal lung lesions can be detected by in utero ultrasonagraphy and treated early by different methods including: fetal thoracocentesis, thoracoamniotic shunting laser therapy or fetal surgical resection.
With accurate diagnosis and preoperative planning these anomalies can be treated safely and effectively.