Congenital lobar emphysema is a rare respiratory disorder in which air can enter the lungs but cannot escape, causing overinflation (hyperinflation) of the lobes of the lung. It is most often detected in newborns or young infants, but some cases do not become apparent until adulthood. Signs and symptoms may include difficulty breathing and respiratory distress in infancy, an enlarged chest, compressed lung tissue, cyanosis, and underdevelopment of the cartilage that supports the bronchial tube (bronchial hypoplasia). This disorder may be severe enough to cause associated heart problems (15% of cases) or so mild as to never become apparent. Some cases may be caused by autosomal dominant inheritance while others occur for no apparent reason (sporadic).