Pulmonary alveolar proteinosis: diagnostic and therapeutic challenges

Pulmonary Alveolar Proteinosis (PAP) is a rare syndrome characterized by pulmonary surfactant accumulation within the alveolar spaces. It occurs with a reported prevalence of 0.1 per 100,000 individuals and in distinct clinical forms: autoimmune (previously referred to as the idiopathic form, represents the vast majority of PAP cases, and is associated with Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) auto-antibodies; GMAbs), secondary (is a consequence of underlying disorders), congenital (caused by mutations in the genes encoding for the GM-CSF receptor), and PAP-like syndromes (disorders associated with surfactant gene mutations). The clinical course of PAP is variable, ranging from spontaneous remission to respiratory failure. Whole lung lavage (WLL) is the current standard treatment for PAP patients and although it is effective in the majority of cases, disease persistence is not an unusual outcome, even if disease is well controlled by WLL. In this paper we review the therapeutic strategies which have been proposed for the treatment of PAP patients and the progress which has been made in the understanding of the disease pathogenesis.