Microscopic Polyangiitis Accompanied by Pleuritis as the only Pulmonary Manifestation of Occupational Silica Exposure

A 68-year-old man, who had worked for processing quartz-containing stones for more than 50 years, complained of low-grade fever and arthralgia. Mediastinal lymph nodes were markedly swollen on chest computed tomography. Pathological findings of the lymph node were compatible with silicosis, with a high titer of myeloperoxidase anti-neutrophil cytoplasmic antibody (MPO-ANCA). During follow-up with prednisolone treatment, pleuritis and uveitis developed as manifestations of vasculitis. Thus, he was diagnosed with MPO-ANCA-associated vasculitis with occupational silica exposure, possibly microscopic polyangiitis (MPA). This case is rare, because pleuritis was the only pulmonary manifestation, without interstitial pneumonia, alveolar hemorrhage or glomerulonephritis.