Vasculitis pathophysiology

Vasculitis
Overview
Classification Large-sized vessel vasculitis Takayasu's Arteritis Temporal Arteritis Medium-sized vessel vasculitis Kawasaki's Disease Polyarteritis Nodosa Small-sized vessel vasculitis Churg-Strauss Syndrome Cutaneous leukocytoclastic vasculitis Essential cryoglobulinemic vasculitis Henoch-Schonlein Purpura Microscopic polyangiitis Wegener's Granulomatosis Variable-sized vessel vasculitis Sjogren syndrome Cogan syndrome Single organ vasculitis Primary central nervous system angiitis
Causes
Differential Diagnosis

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: M.Umer Tariq [2]

Pathophysiology

Large vessel vasculitis

• Takayasu arteritis - Primarily affects the aorta and its main branches.
• Giant cell (temporal) arteritis - Chronic vasculitis of both large and medium vessels, primarily affecting cranial branches of the arteries arising from the aortic arch.

Medium vessel vasculitis

• Polyarteritis nodosa - Systemic necrotizing vasculitis and aneurysm formation affecting both medium and small arteries. If only small vessels are affected, it is called microscopic polyangiitis, although it is more associated with Wegener's granulomatosis than to classic PAN.
• Wegener's granulomatosis - Systemic vasculitis of medium and small arteries, including venules and arterioles. Produces granulomatous inflammation of the respiratory tracts and necrotizing, pauci-immune glomerulonephritis. Most common cause of saddle nose deformity in USA (nose flattened due to destruction of nasal septum by granulomatous inflammation).
• Kawasaki disease - Usually in children, it affects large, medium, and small vessels, prominently the coronary arteries. Associated with a mucocutaneous lymph node syndrome.
• Isolated CNS vasculitis - Affects medium and small arteries over a diffuse CNS area, without symptomatic extracranial vessel involvement.

Small vessel vasculitis

• Churg-Strauss arteritis - affects medium and small vessels with vascular and extravascular granulomatosis. Classically involves arteries of lungs and skin, but may be generalized.
• Microscopic polyarteritis/polyangiitis - affects capillaries, venules, or arterioles. Thought to be part of a group that includes Wegeners since both are associated with ANCA and similar extrapulmonary manifestations. Patients do not usually have symptomatic or histologic respiratory involvement.
• Hypersensitivity vasculitis - usually due to a hypersensitivity reaction to a known drug. There is presence of skin vaculitis with palpable petechiae or purpura. Biopsy of these lesions reveal inflammation of the small vessels, termed leukocytoclastic vasculitis, which is most prominent in postcapillary venules.
• Henoch-Schonlein purpura - systemic vasculitis due to tissue deposition of IgA-containing immune complexes. Biopsy of lesions shows inflammation of small vessels. It is considered a form of hypersensitivity vasculitis but is distinguished by prominent deposits of IgA. This is the most common vasculitis in children.
• Essential cryoglobulinemic vasculitis - most often due to hepatitis C infection, immune complexes of cryoglobulins --- proteins that consists of immunoglobulins and complement and precipitate in the cold while dissolving upon rewarming --- are deposited in walls of capillaries, venules, or arterioles.
• Vasculitis secondary to connective tissue disorders - usually secondary to systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), relapsing polychondritis, Behcet's disease, and other connective tissue disorders.
• Vasculitis secondary to viral infection

Gross Pathology

Images courtesy of Professor Peter Anderson DVM PhD and published with permission © PEIR, University of Alabama at Birmingham, Department of Pathology

Kidney: Petechiae: Gross natural color, an excellent example of flea bitten kidney case had necrotizing vasculitis

Skin:Leucocytolastic vasculitis; a close up view

Microscopic Pathology

Kidney: Transplant: Micro H&E high mag excellent example acute vasculitis due to rejection

Coronary artery: Transplant Rejection: Micro high mag H&E small muscular artery vasculitis

Vasculitis, Rocky Mountain Spotted Fever, immunoperoxidase staining vessels for Rickettsia rickettsii