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Vasculitis Dr. Gehan Mohamed Dr. Abdelaty Shawky * Definition: • Inflammation of the blood vessels • Clinically often include constitutional signs and symptoms such as fever, myalgia, arthralgia, and malaise, or local manifestations of tissue ischemia. * Causes of vasculitis: 1. infection: pathogens either cause direct invasion of vascular walls or indirectly induce a noninfectious, systemic immune-mediated vasculitis, for example, by generating immune complexes or triggering cross-reactivity. 2. Physical and chemical injury: such as irradiation, mechanical trauma, and toxins can also cause vascular damage. 3. immune-mediated vasculitis: the vascular wall is damaged by different immune mechanisms; a. Immune complex deposition: as in hypersensitivity to drugs, hepatitis B virus infection b. Anti-neutrophil cytoplasmic antibodies (ANCAs): ANCAs are a heterogeneous group of autoantibodies directed against enzymes mainly found within the primary granules in neutrophils, in the lysosomes of monocytes, and in endothelial cells. - The description of these autoantibodies is based on the immunofluorescent patterns of staining. - Two main patterns are recognized: one shows cytoplasmic localization of the staining (c-ANCA), and the most common target antigen is proteinase-3 (PR3), a neutrophil granule constituent. The second shows perinuclear staining (p-ANCA) and is usually specific for myeloperoxidase (MPO). - The disorders characterized by circulating ANCAs are called the ANCA-associated vasculitis. c. Anti-endothelial cell antibodies: • Antibodies to ECs, perhaps induced by defects in immune regulation, may predispose to certain vasculitis, such as those associated with SLE and Kawasaki disease. * Classification of vasculitis: • The systemic vasculitis are classified on the basis of : - the size and anatomic site of the involved blood vessels - histologic characteristics of the lesion, and - clinical manifestations. There is considerable clinical and pathologic overlap among these disorders 1. GIANT CELL (TEMPORAL) ARTERITIS - Is the most common form of systemic vasculitis in adults. - Affects old ages above the age of 50 years. - Is granulomatous inflammation of large sized arteries. - It affects principally the head arteries especially the temporal arteries, but also the vertebral and ophthalmic arteries and the aorta. Ophthalmic arterial involvement may lead to permanent blindness. * Morphology: • Characteristically, segments of affected arteries develop nodular thickenings with reduction of the lumen and may become thrombosed. • Microscopically: granulomatous inflammation of the inner half of the media showing mononuclear infiltrate, multinucleate giant cells and fragmentation of the internal elastic lamina. • The healed stage reveals collagenous thickening of the vessel wall with organization of the luminal thrombus. • Sometimes transforms the artery into a fibrous cord. * Pathogenesis: immunologic reaction against elastin. * Clinical Features: - Constitutional manifestations: fever, fatigue, weight loss. - Facial pain or headache, often most intense along the course of the superficial temporal artery, which may be painful to palpation. - Ocular symptoms (associated with involvement of the ophthalmic artery). 2. TAKAYASU ARTERITIS • The illness is seen predominantly in females younger than age 40. • This is a granulomatous vasculitis of large sized arteries especially aorta and ocular arteries. • Clinically characterized principally ocular disturbances and marked weakening of the pulses in the upper extremities (pulseless disease). * Morphology: • Grossly: The affected vessel shows irregular thickening with intimal wrinkling. • Microscopically: adventitial mononuclear infiltrate with perivascular cuffing of the vasa vasorum and granulomatous inflammation, with giant cells. • Later, there is collagenous fibrosis involving all layers of the vessel wall. 3. POLYARTERITIS NODOSA (PAN) • PAN is a systemic vasculitis of small or mediumsized muscular arteries (but not arterioles, capillaries, or venules), e.g. renal artery. • Clinical manifestations result from ischemia and infarction of affected tissues and organs. • Affects young adults. • The course may be acute, subacute, or chronic. • The disease is fatal in most cases, either during an acute fulminant attack or following a protracted course, but therapy with corticosteroids and cyclophosphamide results in remissions or cures in 90% of cases. * Morphology: • Segmental transmural necrotizing inflammation with neutrophils ,eosinophils and fibrinoid necrosis. • The lumen may become thrombosed. • Later, the acute inflammatory infiltrate disappears and is replaced by fibrous thickening of the vessel wall that may extend into the adventitia. • Firm nodularity sometimes marks the lesions. * Complications of PAN: 1. Thrombosis with subsequent ischaemic complications. 2. Aneurysmal dilatation. 3. Rupture during acute attacks with fatal hemorrhage. 4. KAWASAKI DISEASE (MUCOCUTANEOUS LYMPH NODE SYNDROME) - It is inflammation of the coronary arteries, usually in young children and infants (80% of cases are <4 years old). - Epidemic in Japan. - It is associated with the mucocutaneous lymph node syndrome, an acute but usually self-limited illness manifested by fever, conjunctival and oral erythema and erosion, edema of the hands and feet, erythema of the palms and soles, a skin rash often with desquamation, and enlargement of cervical lymph nodes. * Morphology: • Fibrinoid necrosis and pronounced inflammation affecting the entire thickness of the vessel wall. * Fate: • Most of cases subsides spontaneously or in response to treatment. • Some cases may be complicated by aneurysm formation, thrombosis, and/or myocardial infarction. • Healed lesions may cause obstructive intimal thickening * Pathogenesis: • Immune reaction characterized autoantibodies to endothelial cells and smooth muscle cells, leading to acute vasculitis. • Viral infection may trigger the disease in genetically susceptible patients. 5. MICROSCOPIC POLYANGIITIS - It is necrotizing vasculitis affects arterioles, capillaries. - In contrast to PAN, the affected vessels are smaller, necrotizing glomerulonephritis (90% of patients) pulmonary capillaritis are particularly common. * Clinical features: Hemoptysis, arthralgia, abdominal pain, hematuria, proteinuria, hemorrhage, and muscle pain or weakness. * Pathogenesis: - Immunologic reaction to an antigen such as drugs (e.g., penicillin), microorganisms (e.g., streptococci), heterologous proteins, and tumor antigens. -In 70% of patients, p-ANCAs are present. 6.WEGENER GRANULOMATOSIS It is a necrotizing granuloma affecting triad of: 1. Respiratory tract. 2. Necrotizing granulomatous vasculitis affecting small to medium-sized vessels, mostly of the lungs and upper airways. (3) Kidney: in the form of glomerulonephritis. 8. THROMBOANGIITIS OBLITERANS (BUERGER DISEASE) • Is characterized by segmental inflammation and , thrombosis of medium-sized and small arteries, principally the tibial and radial arteries • Sometimes secondarily extending to veins and nerves of the extremities. • Affects heavy cigarette-smoking men and women usually before age 35 in most cases. • Direct endothelial cell toxicity by some tobacco products or hypersensitivity to them. • Stopping smoking in the early stages of the disease often prevents further attacks. 8. VASCULITIS ASSOCIATED WITH OTHER DISORDERS • Such as rheumatoid arthritis, SLE, malignancy. References: Robbins and Cotran’s: Pathologic Basis of Disease. Seventh edition. Thanks