IS Case 256: Congenital lobar emphysema
Imaging Sciences URMC 2009
Publication Date: 2009-06-26
Initial radiograph demonstrated hyperinflation of the left upper lobe with mediastinal shift towards the left. Subsequently, bilateral decubitus films demonstrated a left lung that remains hyperlucent on both decubitus views. A chest CT was then done that confirmed the diagnosis of congenital lobar emphysema.
Congenital lobar emphysema (CLE) is a developmental anomaly of the lower respiratory tract involving one or more lobes. It is characterized by overdistension and air trapping in the affected lobe, with concomitant compression of the remaining lung tissue and also displacement of the mediastinum by herniation of the emphysematous lobe across the anterior mediastinum into the opposite chest. CLE is a rare anomaly with a prevalence of 1 in 20,000 to 1 in 30,000. There is a male predominance of 3:1.
CLE is the final result from multiple and various disruptions in bronchopulmonary development due to abnormal interactions between the endodermal and mesodermal components of the lung. These disruptions may lead to alterations in the number and sizes of alveoli with the final outcome of progressive lobar hyperinflation. The most common identified cause of CLE is obstruction of the developing airway. This obstruction may be intrinsic such as a defect in the bronchial wall or extrinsic, such as compression caused by vascular anomalies or an intrathoracic mass.
The diagnosis of CLE may be made from the characteristic chest radiography appearance which typically demonstrates distension of the affected lobe and mediastinal shift, with compression and atelectasis of the contralateral lung. When the chest radiograph is obtained immediately after birth, the affected lobe may appear opaque due to retained fetal lung fluid. CT of the chest or magnetic resonance imaging may be used to confirm the diagnosis while also demonstrating a source of obstruction.
The differential diagnosis associated with the radiographic appearance of CLE includes pneumothorax, and localized pulmonary interstitial emphysema. The emphysematous lobe in CLE usually has linear bronchovascular and alveolar markings, differentiating it from pneumothorax. Localized PIE is usually a sequale of high airway pressure mechanical ventilation. Congenital cystic adenomatoid malformation (CCAM), bronchopulmonary sequestration (BPS), bronchogenic cyst, and congenital diaphragmatic hernia may also result in radiographic findings similar to CLE.
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