Christopher P. Coppola, Alfred P. Kennedy, Jr. and Ronald J. Scorpio (eds.)Pediatric Surgery2014Diagnosis and Treatment10.1007/978-3-319-04340-1_30
© Springer International Publishing Switzerland 2014
Congenital Lung Malformations
(1)
Department of General Surgery, Janet Weis Children’s Hospital, 100 N. Academy Av. MC 21-70, Danville, PA 17822, USA
Abstract
Congenital lung malformations are a rare but important disorder which can be associated with significant morbidity and mortality. The malformation may be identified during prenatal sonography, presented as respiratory distress in the newborn, or be completely asymptomatic and incidentally discovered in an adult.
Congenital lung malformations are a rare but important disorder which can be associated with significant morbidity and mortality. The malformation may be identified during prenatal sonography, presented as respiratory distress in the newborn, or be completely asymptomatic and incidentally discovered in an adult.
1.
Pathophysiology:
(a)
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Congenital pulmonary airway malformation (CPAM).
(i)
Previously known as cystic adenomatoid malformation (CCAM), CPAM is rare but is one of the most common congenital lung abnormalities. It is the second most common cause (25 %) of newborn respiratory distress.
(ii)
The lesions are hamartomatous proliferation of cysts comprised of adenomatous elements and resemble bronchioles.
(iii)
They have connections with the tracheobronchial tree. The arterial supply and venous drainage from the lesions are typically with pulmonary circulation though they can be from systemic circulation.
(iv)
CPAM are classified into one of five types based on the size and the characteristics of the tissue.
1.
Type 0- These lesions arise from the tracheal or bronchial tissue and are the rarest form. The cysts are small and involve the entire lung. Affected infants die at birth due to severely impaired gas exchange.
2.
Type 1-This type comprises about 60–70 % and is the most common form. It originates from the distal bronchi or proximal bronchioles and consists of well-differentiated tissue. The cysts are usually single but may be multi-loculated. The majority of the cases involve only one lobe of the lung. It has malignant potential.
3.
Type 2-This type comprises about 15–20 % of cases and consists of multiple cysts that blend into adjacent normal tissue. The lesions resemble dilated terminal bronchioles. Up to 60 % of cases have other congenital anomalies. It does not have malignant potential.
4.
Type 3- These lesions comprise about 5–10 % of cases and are often very large proliferating from the distal airways or airspaces and involving an entire lobe or several lobes. This type has not been associated with malignancy.
5.
Type 4-These lesions comprise 10–15 % of cases and have a maximum diameter of 7 cm. They are strongly associated with malignancy.
(v)
Previously used classification system for CCAM:
1.
Macrocystic: 13 %; has cysts >5 mm in diameter.
2.
Microcystic: 73 %; all cysts <5 mm, resemble bronchioles.
3.
Solid: 13 %; microscopic cysts.
(vi)
Lesions can be multifocal and even bilateral.
(vii)
During gestation, compression of heart/central veins by CPAM can lead to hydrops. Compression of GI tract (esophagus) can lead to polyhydramnios.
(viii)
Course over time: some prenatally diagnosed CPAM lesions will shrink and disappear on postnatal imaging. If it persists to age 6-months-old it is unlikely to resolve.
(ix)
Risk of pneumonia: compression of the lesion on bronchial passages leads to overinflation of distal alveoli, trapping of air and mucus, and recurrent pneumonia, which makes future resection more difficult with increased blood loss.
(x)
Risk of Neoplasm: if not treated, certain types of CPAM can develop into malignancy such as broncoalveolar carcinoma, sarcoma, or pulmonary blastoma.
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