RESUMO
Microscopic polyangiitis (MPA) is a distinct type of systemic small vessel vasculitis affecting small sized vessels with few or no immune deposit and no granulomatous inflammation. Cause or pathogenetic mechanism of MPA has been unknown but association with silicon or silica exposure or pulmonary silicosis has been reported rarely and supports hypothesis that environmental factors are important modulating or triggering factors of the vasculitis in the indivisual who may be genetically predisposed. We report a case of microscopic polyangiitis with underlying pulmonary silicosis in 43 year-old male. He was admitted due to hemoptysis, dyspnea, fever and bilateral pulmonary infiltration with underlying small nodular densities in whole lung field and egg-shell calcification of both hilar areas. Laboratory findings showed hematuria, proteinuria and rapid deterioration of renal function. Renal biopsy revealed focal segmental necrotizing glomerulonephritis with early cellular crescents accompanied with membranous glomerulonephropathy and perinuclear-antineutrophil cytoplasmic antibody was positive. Under the diagnosis of MPA, he has been managed with high dose steroid, cyclophosphamide and hemodialysis. Chest infiltration decreased and hemoptysis and hypoxia was improved but renal function was not recoverd and he needed regular hemodialysis continuously.