Lung, surfactant dysfunction disorder

Surfactant dysfunction disorders are a group of diseases caused by the defective production of pulmonary surfactant. Surfactant is responsible for maintaining surface tension within the oxygen-exchange areas of the lung. They occur predominantly in infants and children, and are caused by inherited or de novo mutations in genes affecting surfactant metabolism. The histologic manifestations of surfactant dysfunction disorders in infancy include different patterns, such as pulmonary alveolar proteinosis (PAP), and desquamative interstitial pneumonia (DIP). Sections of this lung show a DIP-like pattern with accumulation of foamy macrophages in the alveoli. There is hyperplastic alveolar epithelium interspersed with thickened hypercellular interstitial septa. Electron microscopy (EM) should be performed in suspected cases to document abnormalities associated with surfactant protein B and ABCA3 mutations (see Related Content section). Genetic testing in this case confirmed the ABCA3 mutation, the most commonly mutated gene in surfactant dysfunction disorders. It is an autosomal recessive disorder. Other affected genes include surfactant proteins C and B.