Occupational exposures associated with pulmonary alveolar proteinosis

Abstract

Introduction: Pulmonary alveolar proteinosis (PAP) is a rare, diffuse lung disease characterized by alveolar filling with lipoproteinaceous material. While most PAP is considered idiopathic, occupational etiologies, such as silica exposure causing “silicoproteinosis,” are recognized. Aim: To systematically review the occupational contributions to PAP. Methods: We identified and reviewed relevant publications through January 2017 using PubMed and manual review of identified papers’ references. We included publications that described at least 10 cases of PAP and that also noted the number with occupations involving likely exposure to various vapors, gases, dusts, and/or fumes (VGDF) or with presumably occupational VGDF exposures. We calculated the prevalence of occupational exposures generally and silica exposure specifically. Results: We included 24 publications with a total of 1413 cases (range: 11-241 cases/publication). The mean prevalence of occupational exposure was 29% (median: 30%, range: 0-59%). Thirteen publications specifically addressed silica exposure; mean prevalence in those studies was 6% (median: 6%, range: 0-22%). Studies that collected information about exposure through questionnaire generally reported a higher prevalence of exposure. Three publications included comparison to controls: one found a higher prevalence of self-reported occupational inhalational exposure in cases (34%) than controls (20%) (p=0.07); two were histopathological investigations of the same cases that found more birefringent particles (p Conclusions: Nearly one third of PAP in cases series is associated with work-related exposures.