Literature
Clinical Pearls & Morning Reports
Published November 13, 2024
There are several congenital malformations that can occur in the lung. Read the NEJM Case Records of the Massachusetts General Hospital here.
Clinical Pearls
Q: Congenital lobar overinflation most often affects which lobe of the lung?
A: Congenital lobar overinflation is a condition that leads to overexpansion of a lobe of the lung. Congenital lobar overinflation is associated with dyspnea and tachypnea. Involvement of the left upper lobe is most common, whereas involvement of a lower lobe is rare.
Q: Can bronchogenic cysts occur in the lung parenchyma?
A: Bronchogenic cysts form when bronchial tissue separates from the airway during development. Such cysts are characteristically thin-walled and lined by ciliated pseudostratified columnar epithelium. Although bronchogenic cysts are predominantly found in the mediastinum, 5% of cases are found in the lung parenchyma, typically in the lower lobe of the lung. Multiple bronchogenic cysts can compress nearby bronchi, which may lead to obstruction and possibly pneumonia.
A: Bronchopulmonary malformations include CPAM and bronchopulmonary sequestration (BPS). CPAM is caused by hamartomatous proliferation of airways during embryonic development and has an incidence of 1 case per 7500 live births. There are five types, each with distinctive clinical and morphologic features that correspond to their airway origins. CPAM type 1 is the most common type, accounting for more than two thirds of all cases, and it is often detected prenatally. CPAM type 1 is characterized by large cysts (measuring up to 10 cm in diameter) that are usually detected on prenatal ultrasound screening and would also be easily identified on chest radiography. CPAM type 2 is the second most common type, accounting for 10 to 15% of all cases. Affected patients present with respiratory symptoms within the first month after birth, and chest radiography shows multiple cystic spaces (measuring up to 2.5 cm in diameter) that result in a spongelike appearance.
A: BPS is a congenital malformation in which lung tissue is not connected to the tracheobronchial tree and the vascular supply to the involved lung parenchyma typically originates from the aorta. The malformation can be categorized as extralobar or intralobar. Extralobar BPS is encapsulated by its own pleura and is typically situated between the lower lobe and the diaphragm. Intralobar BPS, which is more common than the extralobar form, is integrated into the normal lung parenchyma and is usually located in a lower lobe (in 98% of cases), particularly in the medial and posterior basal segments of the left lower lobe. In patients with BPS, the lung parenchyma is not connected to the tracheobronchial tree; however, intralobar BPS is connected to the alveoli of the normal lung by the pores of Kohn, through which bacterial contamination can occur, leading to infection. Infection occurs in up to 70% of patients with intralobar BPS, with symptoms of infection developing as early as 6 months of age.