Microscopic polyangiitis with unusual lung involvement.

Microscopic polyangiitis (MPA) is a non-granulomatous, systemic and small vessel vasculitis accompanied by segmental necrotizing glomerulonephritis with no evidence of other small vessel disease. We report a patient with weakness, fever, and arthralgia whose CXR and thoracic CT showed widespread nodular infiltration. His proteinase-3 anti-neutrophilic cytoplasmic antibody (c-ANCA) was positive. The serum creatinine was increased and haematuria subsequently developed. Renal biopsy revealed a focal segmental necrotizing glomerulonephritis which was compatible with MPA. He was treated with high-dose corticosteroid and cyclophosphamide. Because of a worsening CXR and hypoxaemia, mechanical ventilation was applied. Despite this he died of respiratory failure following 20 days of treatment. Nodular infiltration is an unusual radiological pattern in patients with MPA and is the reason for this report.