Significant but Temporary Efficacy of Statin for a Patient With Severe Autoimmune Pulmonary Alveolar Proteinosis: A Case Report

Autoimmune pulmonary alveolar proteinosis (APAP) is a rare autoimmune lung disorder characterised by the presence of anti-granulocyte-macrophage colony-stimulating factor (GM-CSF) antibodies. Whole-lung lavage (WLL) therapy remains the standard treatment for severe cases. Recently, inhaled GM-CSF therapy has been approved in Japan; however, the cost of the treatment remains a limiting factor. Several reports have suggested that oral statin therapy may be a promising therapeutic option for APAP. Herein, we report a case of severe APAP that underwent WLL therapy twice and achieved an excellent response and remarkable clinical resolution of respiratory failure after the initiation of oral statin therapy. Remarkable improvements in oxygen saturation, blood gas analysis, serum biomarker levels and pulmonary function test results were observed after statin administration. However, the efficacy was temporary, and respiratory failure relapsed 2 years after the initiation of statin therapy. Statin therapy for APAP was deemed effective but potentially temporary.