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an inflammatory reaction in a blood vessel, the result of a specific reaction to an antigenic (allergic) substance or other agents to which the individual expresses unusual vascular sensitization.
microscopic polyangiitisA systemic small-vessel vasculitis that primarily affects the kidneys, skin, and lungs of middle-aged men.
Fever, malaise, myalgia, weight loss, and autoimmunity, including antineutrophil cytoplasmic antibodies (p-ANCA). Skin lesions occur in 30 to 50%, usually presenting as purpura due to leukocytoclastic vasculitis, less commonly as nodules involving the vessels of the dermis and subcutaneous fat and ulcers. The kidney shows rapidly progressive focal and segmental glomerulonephritis.