Alveolar proteinosis – disease with unpredictable evolution (series of clinical cases)

Pulmonary alveolar proteinosis (PAP) is a rare disease, certainly underdiagnosed, characterised by the intra-alveolar accumulation of a milky fluid rich in phospholipids and lipoproteins derived from alveolar surfactant, positive in periodic acid-Schiff staining. The alveolar macrophage plays a major role in the pathogenesis of PAP, and its role in the turn-over of alveolar surfactant is being altered by various mechanisms.

More than 90% of cases of PAP are primary autoimmune, characterised by the presence in serum of circulating autoantibodies against granulocyte-macrophages colony-stimulating factor. Other causes of PAP are genetic, secondary to other diseases or to exposure to different agents.

The evolution of the disease is unpredictable, from spontaneous remission to progression despite treatment towards pulmonary fibrosis and chronic severe respiratory failure. The gold standard of therapy is the whole lung lavage, other treatments are being still in evaluation.

The article presents a few cases that illustrate different patterns in the evolution of PAP.