Vasculitis: classification, pathomorphology, Types of aneurysms
Vasculitis is vessel wall inflammation, it can affect small or large vessels, different types of vasculitis have different preferences (there are 20 different primary forms of vasculitis). We generally divide vasculitis into arteritis and phlebitis.
Classifications can be as follows:
- Based on etiology
- Infectious
- Autoimmune/immune mediated
- Based on location of affected vessels
- Vasculitis limited to skin
- Necrotizing vasculopathies
- Musculoskeletal vasculitis
- Type blood vessels
- Arteritis
- Phlebitis
- Size of blood vessel
- Large (e.g. Takayasu’s arteritis, Temporal arteritis)
- Medium (e.g. polyarteritis nodosa)
- Small (e.g. eosinophilic granulomatosis with polyangiitis)
Many patients with vasculitis have circulating Anti-neutrophil cytoplasmic antibodies, which are directed at enzymes of neutrophil primary granules, monocytes lysosomes and endothelial cells. They are a useful diagnostic marker for immune-associated vasculitis as well as having a close relationship with the severity of the vasculitis.
Example: c-ANCA (anti-proteinase 3) points to granulomatosis with polyangiitis (Wegener); p-ANCA (anti-myeloperoxidase) points to microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis (Churg–Strauss). Polyarteritis nodosa is typically ANCA-negative.
Here we will evaluate some of the most common vasculitis types:
- Giant cell (temporal) arteritis
- Most common form of vasculitis in elderly in developed countries
- Is a chronic, granulomatous inflammation of large/small arteries, especially temporal arteries
- Can cause blindness if not treated
- Pathogenesis is a T-cell mediated immune response to vessel wall antigens causing granulomatous inflammation
- Artery exhibits patchy nodular intima thickening and occasional thromboses, with lumen narrowing and classic granulomatous inflammation and fragmentation of the internal elastic lamina.
- Clinical signs include fever, fatigue, facial pain/headache that is most severe on superficial temporal side, and most importantly, painful palpation of the temporal artery
- Takayasu arteritis
- Granulomatous vasculitis of medium and larger arteries characterised by ocular disturbances and weakened brachial pulse.
- Mainly causes transmural scarring and thickening of aorta (arch and great vessels most commonly affected).
- Inflammation is associated with intimal hyperplasia, adventitial fibrosis and irregular patches of thickening.
- Polyarteritis nodosa
- Systemic vasculitis of small or medium-sized arteries, particularly renal and visceral vessels
- It causes a form of necrotizing inflammation often with thrombosis. Kidney, heart liver and GI tract are all affected, lesions generally affect only part of the vessels circumference. Causes weakening of the vessels increasing risk of ulcerations, infarcts, ischemic atrophy and hemorrhages.
- It is predominantly a disease of young people, clinical course is generally chronic with acute episodes. Classic presentation can see a combination of rapidly increasing hypertension, bloody stools and diffuse muscular pains and neuropathies.