Classification of pulmonary alveolar proteinosis in newborns, infants, and children

Pulmonary alveolar proteinoses are rare pulmonary diseases characterised by an intraalveolar accumulation of surfactant protein A. Subtyping of alveolar proteinoses: Type I alveolar proteinoses: severe respiratory insufficiency in newborns, which will take a lethal course without lung transplant; hereditary SP-B deficiency and an intraalveolar accumulation of N-terminal incompletely processed SP-C. Type II alveolar proteinoses: occur in newborns and infants; often take a lethal course; show intraalveolar accumulation of precursors of SP-B and mature SP-B as well as an accompanying interstitial lung disease of variable severity. Type III alveolar proteinoses: in infants and children; do not generally take a lethal course; they are characterised by an intraalveolar accumulation of precursors of SP-B and mature SP-B without accompanying interstitial lung disease. "Cryptogenic" congenital, acquired (idiopathic), and secondary type III alveolar proteinoses can be distinguished. In newborns, infants, and children with pulmonary alveolar proteinosis, a detailed pathological-anatomical examination including immunohistochemical and molecular genetic analyses, should be performed in order to optimise the therapeutical management.