<unk>  is the complete absence of lung tissue, including bronchial tree, lung parenchyma, and supporting vasculatures. The only remaining part is rudimentary bronchus. Hence, the affected areas lose their function of gas exchange. This malformation is thought to involve the proliferation arrest of lung buds during embryo development, while the causes are still debatable. In many cases, it is associated with the occurrence of other inborn malformations. The estimated prevalence of<unk>  is 34/1,000,000 live births, with a slightly higher possibility in the female population. Two types of<unk>  are classified based on the severity of underdevelopment: bilateral and unilateral<unk> . Bilateral<unk>  Bilateral<unk>  means that both sides of the lung are absent, its occurrence is rare compared to unilateral<unk> . The fetus losses the ability to do gas change, and is hence incompatible with life after birth. Unilateral<unk>  The severity of unilateral<unk>  varies depending on the area of tissue affected, being either a single lobe or a whole lung. The clinical features varies in individuals from asymptomatic to various respiratory complaints. The occurrences of symptoms also vary from infant stage to childhood, teenager, and adult life. Frequently seen clinical features includes dyspnea, respiratory distress, recurrent pulmonary infections, and limited exercise tolerance. Rapid heartbeat, cyanosis, chest asymmetry, dullness may also be present. Lung function is significantly affected in cases of<unk> , demonstrated by reduction in forced expiratory volume and forced vital capacity. This reduction in total lung volume sets limits on patients’ exercise tolerance, and contribute to shortness of breath after exercises. The retention of bronchial secretions often leads to recurrent pulmonary infections, adding to damage in lung function, hence causing respiratory stress. Associated anomalies Considering the fact that a large proportion of mortality cases of<unk>  are partly due to the presence of associated malformations, it is common to find other congenital anomalies associated with this type of disorder. Although some cases of bilateral<unk>  were reported as an isolated finding, most cases of<unk>  are associated with other anomalies, especially in the gastrointestinal, genitourinary and ocular systems. Frequently associated congenital anomalies include tracheal stenosis, esophageal atresia, tracheoesophageal fistula, bronchogenic cysts, patent ductus arteriosus, tetralogy of Fallot and anomalies of the great vessels.
Pulmonary agenesis
Pulmonary atresia
Tracheal agenesis
Pulmonary hypoplasia
Situs ambiguus
Renal agenesis
Congenital diaphragmatic hernia
Double aortic arch