Congenital lobar emphysema (CLE) is a developmental anomaly of the lower respiratory tract that is characterized by hyperinflation of one or more of the pulmonary lobes [1,2]. Other terms for CLE include congenital lobar overinflation and infantile lobar emphysema [3-5].
Congenital lobar emphysema (CLE) is a rare congenital malformation with a prevalence of 1 in 20,000 to 1 in 30,000 . CLE was diagnosed in 10 of 70 patients with congenital malformations of the lung seen from 1970 to 1995 at Children's National Medical Center in Washington, DC . Depending upon the pattern of referrals, other tertiary medical centers may treat one or two cases per year [3,8].
Males appear to be affected more than females, in a ratio of 3:1 . The reason for the male predominance is unknown [1,3,5].
Progressive lobar hyperinflation is likely the final common pathway that results from a variety of disruptions in bronchopulmonary development. These result from abnormal interactions between embryonic endodermal and mesodermal components of the lung. Disturbances may lead to changes in the number of airways or alveoli or alveolar size . However, a definitive causative agent cannot be identified in approximately 50 percent of cases .
The most frequently identified cause of congenital lobar emphysema (CLE) is obstruction of the developing airway, which occurs in 25 percent of cases . Airway obstruction can be intrinsic or extrinsic, with the former more common. This leads to the creation of a "ball-valve" mechanism in which a greater volume of air enters the affected lobe during inspiration than leaves during expiration, producing air trapping.