Rare diseases bullet 6: Pulmonary alveolar proteinosis: clinical aspects and current concepts on pathogenesis

Pulmonary alveolar proteinosis was first described by Rosen et al in 1958. 1 It is an unusual diVuse lung disease characterised by the accumulation of large amounts of a phospholipoproteinaceous material in the alveoli.It has a variable clinical presentation and course.Most cases are primary but occasionally the condition is secondary to other conditions or inhalation of chemicals.Whole lung lavage remains the most eVective treatment and the overall prognosis is good.Surfactant homeostasis is abnormal and animal experiments suggest that this may relate, in some instances at least, to defects in GM-CSF signalling.There are at least two congenital forms of the disease and several diVerent animal models suggesting that pulmonary alveolar proteinosis is unlikely to be a single disease entity and more likely to represent a clinical syndrome. EpidemiologyPulmonary alveolar proteinosis is a rare lung disease and accurate estimates of incidence are not available.Current estimates suggest an incidence of one in two million people.2]3456789 However, there are reports of the disease occurring in neonates, 12 children, 131415 and the elderly. 11