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Inflammatory vascular diseases
Leukocytoclastic vasculitis (LCV)
Key Features
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Perivascular infiltrate with neutrophils
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Karyorrhexis (nuclear dust, leukocytoclasis)
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Expansion of the vessel wall
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Fibrin deposition within the vessel wall
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Erythrocyte extravasation
Clinical lesions of leukocytoclastic vasculitis are purpuric and often palpable. Vasculitis involving arterioles commonly produces livedo reticularis or stellate infarcts.
Classification of vasculitis
Vasculitis is classified by the type of inflammatory infiltrate, type of vessel involved, the presence or absence of endothelial necrosis, associated systemic findings, immunofluorescent patterns, and serologic findings. American College of Rheumatology (ACR) classification criteria are mostly clinical, with little emphasis on histologic findings. The Chapel Hill criteria include histologic features, especially vessel size. Because many entities demonstrate involvement of vessels of various sizes, any classification will have limitations.
Large vessel vasculitis
When a large vessel is involved by vasculitis, it is critical to determine whether the involved vessel is an artery or a vein. Arteries are characteristically round, with a wreathlike muscularis and an internal elastic membrane. Veins are characteristically oval, with a bundled muscularis. They may have visible valves and lack an internal elastic membrane. So-called arterialization of veins occurs when they are subjected to elevated hydrostatic pressure. This phenomenon is occasionally noted in cutaneous vessels, but is best demonstrated in coronary artery bypass grafts. The grafted vein develops a prominent internal elastic membrane, but retains the bundled muscularis characteristic of a vein.
Giant cell arteritis (temporal arteritis)
Key Features
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Muscular artery with wreathlike muscularis and prominent internal elastic membrane
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Subendothelial granulomatous inflammation
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With progression, becomes transmural inflammation
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Incidental atherosclerotic changes (calcification, subintimal plaques) often present in the vessel
Temporal arteritis often involves the vessel in a focal, beaded fashion, so an adequate length of temporal artery (ideally 2 cm) should be submitted for examination.
Chapel Hill criteria
Granulomatous arteritis involving the major branches of the aorta, with a predilection for the extracranial branches of the carotid artery. The temporal artery is frequently involved. Patients are usually >50 years of age. Frequently associated with polymyalgia rheumatica.
American College of Rheumatology criteria
Age >50; new headache; abnormal temporal artery clinically; elevated sedimentation rate; positive temporal artery biopsy (three criteria give >93% sensitivity, >91% specificity).
Takayasu arteritis
Key Features
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Granulomatous vasculitis involving large muscular arteries
Chapel Hill criteria
Granulomatous arteritis involving the aorta and its major branches. Usually <50 years of age.
American College of Rheumatology criteria
Age <40; claudication; decreased pulses; >10 mmHg difference in pressure between arms; bruits; abnormal arteriogram (three criteria give >90% sensitivity, >97% specificity).
Polyarteritis nodosa
Key Features
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Large artery involved, typically in the deep dermis or subcutaneous tissue
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Often involves branch points of vessels
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Acute phase is neutrophilic with karyorrhexis
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Chronic phase may demonstrate a granulomatous component
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Fat necrosis is common
Polyarteritis nodosa commonly presents with livedo reticularis and subcutaneous erythematous or hyperpigmented nodules. The biopsy typically demonstrates neutrophilic vasculitis involving an artery within the subcutaneous fat. Surrounding lobular necrosis is present.
Chapel Hill criteria
Necrotizing inflammation involving medium or small arteries without glomerulonephritis or vasculitis in arterioles, capillaries, or venules.
American College of Rheumatology criteria
Weight loss >4 kg; livedo reticularis; testicular pain or tenderness; myalgia/myopathy or muscle tenderness; neuropathy; hypertension (diastolic >90); renal impairment; hepatitis B infection; abnormal arteriogram; biopsy of an artery with neutrophilic inflammation (three criteria give >82% sensitivity, >86% specificity).
Thrombophlebitis
Key Features
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Vasculitis involving an oval vessel with bundled muscularis
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Vessel lacks an internal elastic membrane and may contain valves
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Thrombus present within vessel
Thromboangiitis obliterans (Buerger disease)
Key Features
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Endarteritis
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Prominent neutrophilic inflammation involving the thrombus
Buerger disease is a rare disease typically seen in male smokers. It is characterized by a combination of acute inflammation and thrombosis of large distal-extremity vessels.
American College of Rheumatology criteria
Age >50; history of smoking; distal peripheral vascular obstructive disease (below knee or elbow); and three additional criteria, such as thrombophlebitis saltans/migrans; involvement of upper extremity; characteristic angiography.
Medium vessel vasculitis
Key Features
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Involves a mix of vessel sizes (postcapillary venules plus larger, deeper vessels)
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Endothelial necrosis is common
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Often antineutrophil cytoplasmic antibody (ANCA) associated
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The most common causes include:
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Granulomatosis with polyangiitis (formerly Wegener's granulomatosis) (commonly c-ANCA/antiproteinase 3)
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Churg–Strauss syndrome (commonly p-ANCA/antimyeloperoxidase)
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Microscopic polyangiitis (commonly p-ANCA/antimyeloperoxidase)
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Septic vasculitis
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Rheumatoid vasculitis
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This group of five disorders is sometimes referred to as the big 5 because the vessels include those bigger than the postcapillary venule and the patients are often in bigger trouble.
These diseases are characterized by leukocytoclastic vasculitis involving vessels larger than the postcapillary venule. The endothelium is frequently necrotic. The biopsy demonstrates a superficial and deep perivascular infiltrate with neutrophils, karyorrhexis, expansion of the vessel wall, fibrin deposition within the vessel wall, and erythrocyte extravasation.
Granulomatosis with polyangiitis (formerly Wegener's granulomatosis)
Key Features
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Leukocytoclastic vasculitis (LCV) involving a mix of vessel sizes (postcapillary venule plus larger, deeper vessels)
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Endothelial necrosis is common
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May involve skin, upper respiratory tract, kidneys
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LCV evolves into stellate abscess (palisaded granuloma with central neutrophils)
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Giant cells present in the granuloma
Granulomatosis with polyangiitis (formerly Wegener's granulomatosis) commonly involves the upper airway. The skin of the nose may become necrotic. Skin lesions may occur in other locations, especially the extremities. The histologic pattern is that of a “big 5” vasculitic disorder. Individual vasculitic foci may evolve into stellate abscesses (palisaded granulomas with a central stellate collection of neutrophils). Multinucleate giant cells are present in the granulomas. Granulomatous vasculitis may be present in medium-sized vessels.
Chapel Hill criteria
Granulomatous inflammation of the respiratory tract; necrotizing vasculitis of small to medium vessels; necrotizing glomerulonephritis common.
American College of Rheumatology criteria
Nasal or oral inflammation; chest x-ray with nodules; infiltrate or cavities; microscopic hematuria or red cell casts; granulomatous inflammation on biopsy (two criteria give >88% sensitivity, >92% specificity).
Differential Diagnosis
Palisaded granulomatous dermatitis with stellate abscess formation may be seen in Granulomatosis with polyangiitis (formerly Wegener's granulomatosis) (giant cells peripherally, neutrophils centrally), Churg–Strauss syndrome (epithelioid cells peripherally, eosinophils centrally), atypical mycobacterial infection, sporotrichosis, nocardiosis, cat scratch disease, lymphogranuloma venereum, and tularemia.
Eosinophilic granulomatosis with polyangiitis (Churg-Strauss syndrome)
Key Features
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Leukocytoclastic vasculitis involving a mix of vessel sizes (postcapillary venule plus larger, deeper vessels)
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Endothelial necrosis is common
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Asthma common
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May involve skin and kidneys
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LCV may produce stellate abscesses (palisaded granuloma with central eosinophils)
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Granuloma composed of epithelioid cells without giant cells
Churg–Strauss syndrome is a vasculitic disorder that commonly presents with a prodrome of asthma. Some cases have been induced by leukotriene inhibitors.
The histologic pattern is that of a “big 5” vasculitic disorder. Palisaded granulomas with central stellate abscesses are commonly seen. Unlike those of Granulomatosis with polyangiitis (formerly Wegener's granulomatosis), these rarely contain multinucleated giant cells and the central abscess is composed of eosinophils rather than neutrophils. Flame figures (eosinophil granules adherent to collagen fibers) similar to those of Well syndrome may be present.
Chapel Hill criteria
Eosinophil-rich and granulomatous inflammation involving respiratory tract; necrotizing vasculitis of small to medium vessels; associated asthma and peripheral eosinophilia.
American College of Rheumatology criteria
Asthma; eosinophilia (>10%); neuropathy; pulmonary infiltrates; paranasal sinus involvement; extravascular eosinophils in tissue (four criteria give >85% sensitivity, >99% specificity).
Microscopic polyangiitis
Key Features
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Leukocytoclastic vasculitis involving a mix of vessel sizes (postcapillary venules plus larger, deeper vessels)
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Endothelial necrosis is common
The histologic pattern is that of a “big 5” vasculitic disorder. Endothelial necrosis is a prominent feature. The histologic pattern, ANCA positivity, and systemic involvement define the syndrome.
Chapel Hill criteria
Necrotizing vasculitis; few or no immune deposits; small to medium vessels involved; necrotizing arteriolitis may be present; necrotizing glomerulonephritis and pulmonary capillaritis common.
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