Microscopic Polyangiitis

Microscopic Polyangiitis is a rare disease that causes inflammation of small blood vessels throughout the body. It mainly affects the kidneys, lungs, and skin, leading to symptoms like shortness of breath, blood in urine, and skin rashes. This inflammation can damage organs by reducing blood flow and causing tissue injury. The condition is part of a group called vasculitis, which means blood vessel inflammation. It can develop suddenly or gradually and may cause serious health problems if untreated. Diagnosis often involves blood tests and imaging to assess organ involvement.

Microscopic Polyangiitis (MPA) is a systemic necrotizing vasculitis primarily affecting small vessels such as capillaries, venules, or arterioles without granuloma formation. It is characterized by pauci-immune glomerulonephritis and pulmonary capillaritis, often associated with myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA). The pathogenesis involves an autoimmune response leading to neutrophil activation and vessel wall damage. Clinically, MPA presents with rapidly progressive glomerulonephritis, pulmonary hemorrhage, and constitutional symptoms. It is distinguished from granulomatosis with polyangiitis by the absence of granulomas and from eosinophilic granulomatosis with polyangiitis by lack of eosinophilia. Early recognition is critical due to the risk of organ failure.