Hypoplastic Lung Disease

Excerpt

Hypoplastic lung disease, or pulmonary hypoplasia, is a rare congenital anomaly characterized by incomplete lung tissue development. This results in impaired gaseous exchange and respiratory insufficiency due to reduced airways, alveoli, and pulmonary parenchyma. While primary idiopathic forms are exceedingly rare, most cases occur secondary to other fetal abnormalities, such as congenital diaphragmatic hernia, oligohydramnios, or thoracic compression.

Schneider's 1912 classification, later modified by Boyden in 1955, categorizes lung development anomalies into 3 types: type 1 (agenesis) involves the complete absence of pulmonary structures; type 2 (aplasia) includes a rudimentary bronchus without parenchyma; and type 3 (hypoplasia) presents with reduced lung cells, airways, and alveoli. The severity of hypoplasia is determined by the timing and nature of the insult during the pseudoglandular stage (5–17 weeks gestation), a critical period when mechanical stimuli and pressure balance drive lung development. Clinical presentations range from fatal respiratory insufficiency in neonates (severe form) to chronic lung disease with recurrent respiratory infections (mild form) in adulthood. This review will explore the pathophysiology, diagnostic approaches, and current management strategies for hypoplastic lung disease, aiming to provide insights into optimizing outcomes for affected individuals.