Vasculitis - clinical features and classification
Just as a side note, plural of vasculitis, vasculitides! Didn’t know that.
We divide up vasculitides based on the size of the vessel, these are:
- Large vessel vasculitis
- Takayasu arteritis
- Giant Cell arteritis
- Medium vessel vasculitis
- Polyarteritis nodosa (see above)
- Kawasaki disease
- Buerger disease
- Small vessel vasculitis
- Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis
- Microscopic polyangiitis
- Granulomatosis with polyangiitis
- Eosinophilic granulomatosis with polyangiitis
- Immune complex small-vessel vasculitis
- Anti Glomerular basement membrane disease
- Cryoglobulinemic vasculitis
- IgA vasculitis (Henoch-Schonlein purpura)
- Hypocomplementemic urticarial vasculitis
Large vessels are considered the aorta, is primary branches and any vessel that is not located within an organ. Medium vessels are the main visceral arteries and their branches,
while small vessels include intraparenchymal arteries as well as arterioles, capillaries and veins.
The classifications are not as clear cut as described above, large vessel vasculitis can affect small arteries, however the divisions are made based on what is predominantly affected. We can also classify based on the underlying cause, the locaiton of the affected vessel or the mechanism of damage (ANCA, Hypersensitivity, CT disease, Giant cell, other).
Vasculitides generally exhibit mixed cell infiltrates, with histopathologic patterns showing leukocytosis, granulomatous findings, lymphoplasmacytic infiltrates, eosinophilic infiltration, necrosis and/or a combination of these findings. Some pathophysiology is common regardless of the size of the vessel. For instance, immune complex deposition is often present (but absent in pauci-immune ANCA vasculitis). Below we consider each group of vasculitis in a bit more detail.
Large-vessel vasculitis
Generally the vasculitis appears to begin in the adventitia. Both Takaysu arteritis and giant cell arteritis have lots of T lymphocytes within the inflamed arterial walls.
Medium-small vessel vasculitis
Here there are different types of pathophysiology, the process may be immune complex mediated, it may be the result of antineutrophil cytoplasmic antibodies (ANCA), due to anti-endothelial cell antibodies or the result of a ‘superantigen’ (proteins produced by microbial pathogens that can stimulate large populations of T cells)
Clinical manifestations
- Large vessel vasculitis
- Takayasu arteritis
- Affects the aorta and its main branches. Arteries become stenosed in a long, tapered smooth manner. The most commonly involved arteries are the subclavian and brachiocephalic arteries.
- Termed the ‘pulseless’ disease as it can take away peripheral pulse
- Patients may develop Takayasu retinopathy, aortic dilation, aortic regurgitation, aneurysm formation and aortic rupture
- Giant cell arteritis
- This is aka Temporal arteritis. Patients present with acute onset of headache, visual disturbances, jaw claudication and scalp tenderness
- Medium vessel vasculitis