Autoimmune Pulmonary Alveolar Proteinosis Complicated with Infections: a Nationwide Surveillance Study in Japan

Introduction: Autoimmune pulmonary alveolar proteinosis (APAP), caused by macrophage dysfunction due to the anti-granulocyte-macrophage colony-stimulating factor autoantibody, is known to be complicated with opportunistic infection. We have already reported frequency of infection was 5.3% (Inoue Y, AJRCCM 2008). Subjects and Methods: Questionnaire about APAP cases complicated with infections, was mailed to 195 hospitals in Japan and was returned from 27 hospitals. Subjects of this study were APAP cases complicated with infections managed in the 27 hospitals. Pathogens, site of infection, and clinical course were examined. Results: Frequency of infection was 27 cases (7.2%) out of 375 APAP cases. Lung comorbidities were COPD (n=3), pneumoconiosis (n=1) and interstitial pneumonia (n=2), and three cases were treated with corticosteroids and/or immunosuppressant. Pathogen was bacteria (n=15), fungus (n=5), mycobacterium (n=6), Nocardia (n=2) and virus (n=1). Tuberculous lymphadenitis (n=2), meningeal cryptococcosis (n=1), aspergillus sinusitis (n=1), herpes simplex virus encephalitis (n=1) occurred out of the lung. Diagnosis of APAP preceded incidence of infection in 20 cases (74%). Disease severity of 6 cases (22.2%) improved after the occurrence of infection. Whole lung lavage could not be performed in 2 cases with infection, one case of which died with respiratory failure. Conclusions: Frequency of infection in APAP cases were similar to the previous report. Infection might improve or deteriorate the clinical course of APAP. Financial support: This study was partially granted from AMED; DLD/14526278 to Y. Inoue and T. Arai and PAP/14526182 to Y. Inoue.