Congenital Lobar Emphysema Congenital lobar emphysema (CLE), also known as congenital lobar hyperinflation (CLH), is caused by overexpansion of the air spaces of a segment or lobe of histologically normal lung (Fig 124.9 ) Operative findings can reveal large blebs protruding from the lung parenchyma (Fig 124.10 ), but often the lobe is anatomically normal in appearance, with the exception of massive overdistention Compression of adjacent normal lung and mediastinal structures frequently occurs, which can result in impairment of gas exchange and lifethreatening circulatory collapse This process is caused by air trapping from either a developmental deficiency of supporting cartilage in the bronchus of a particular lobe or a partially obstructing bronchial lesion, either endobronchial or from external compression (as with a bronchogenic cyst) FIGURE 124.9 Congenital lobar emphysema of the left upper lobe in a 3-month-old girl who presented with decreased breath sounds and rales in this area Note the left-sided secondary compression atelectasis of the lower lobe Clinical Recognition