allaboutdpt

 Polyarteritis Nodosa Polyarteritis nodosa (PAN) is a systemic vasculitis of small- or medium-sized muscular arteries; it typically involves the renal and visceral vessels and spares the pulmonary circulation. There is no association with ANCAS , but one-third of patients have chronic hepatitis B infection, which leads to the formation of immune complexes containing hepatitis B antigens that deposit in affected vessels. The cause is unknown in the remaining cases. Pathogenesis of PAN Immune complex–mediated vasculitis , often linked to Hepatitis B . Immune complexes deposit in medium-sized arteries. Activate the complement  system → recruit neutrophils . Causes fibrinoid necrosis and inflammation of the vessel wall. Leads to thrombosis , aneurysms , and organ ischemia . Not associated with ANCA . Morphology of PAN Classic PAN is a segmental transmural necrotizing inflammation of small- to medium-sized arteries, often with superimposed thrombosis. Kidne...