Pulmonary alveolar proteinosis (PAP) is a rare syndrome characterized by the intra-alveolar accumulation of surfactant lipids and proteins. The aim of the study is to describe the epidemiologic, clinical, physiologic, and laboratory features of PAP in a large single-center cohort of patients with PAP.

Over 30 years, 70 patients with PAP were managed at our institution, 64 with primary and 6 with secondary PAP.

The mean age at diagnosis was 43 years with a male to female ratio of 1.3. BAL was the most commonly applied diagnostic method, performed in 83% of cases. A history of smoking was seen in 79%, and of dust exposure in 54%, most commonly to aluminum, silica and sawdust. GM-CSF autoantibody correlated with clinical outcome and KL-6 with diffusing capacity. The number of whole lung lavages (WLL) necessary to reach remission was higher in current smokers.

This study shows that the use of BAL for the diagnosis of PAP can reduce the need of histological confirmation. A history of dust or fume inhalation is strongly associated with PAP, also with the autoimmune form. Smoking seems to influence the response to treatment, increasing the number of WLL necessary to reach remission.