ABSTRACT
Congenital lung abnormalities are uncommon and diverse in their presentation. However, all those who care for infants and children must have an appreciation for the diagnosis and treatment of these anomalies because the potential consequences can be life threatening. In order to understand the pathophysiology of these malformations, a basic understanding of the embryology of lung development as well as respiratory physiology and anatomy is required and these are briefly presented later. Classical lesions including congenital lung cysts, cystic adenomatous malformation, pulmonary sequestration and lobar emphysema will be considered in some detail later, as well as a number of the less common anomalies.
During the third week of gestation, the human embryo develops a diverticulum of the ventral foregut, which forms the primordium of the respiratory system. This is mainly of endodermal origin; however, cartilaginous and muscular elements will be derived from the splanchnic mesoderm that surrounds the primitive foregut. As the respiratory diverticulum grows caudad, it becomes separated from the foregut by the lateral esophagotracheal ridges, which fuse to form a septum at the end of the fourth gestational week. Thus, the dorsal esophagus and the more ventral trachea and lung buds are defined. The larynx, which is formed from the fourth and sixth branchial arches, maintains communication between the pharynx and the trachea.
