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© Dirk Biddle
The term vasculitis refers to the inflammation of blood or lymph vessels. Directly synonymous is the term angiitis. A particular form - literally meaning “inflammation of the arteries” - is arteritis. The group of disorders broadly classified as vasculitis conditions are known in the plural as the vasculitides (pronounced vas.que.lit.eye.deez).
Vasculitis can affect either the lining (endothelium) or the wall (or mural structures) of an artery or vein. Vasculitis may be defined by the presence of white blood cells (leucocytes) in the blood vessel wall with consequent inflammatory damage to the mural structures. The swelling caused by reactive inflammation can lead to decreased blood flow (ischemia), resulting in localised areas of oxygen deficit (hypoxia), or to a complete obstruction leading to areas of tissue death (necrosis) in some or all of an organ (infarction). Ischemia and infarction can also lead to nerve damage (neuropathy). Inflammatory damage may also weaken a blood vessel walls, causing abnormal dilations (aneurysms) which may in turn rupture and allow bleeding through the weakened blood vessel wall (haemorrhage).
The vasculitides are considered to be autoimmune diseases, where an often unknown pathogen and/or possibly genetic “malfunction” somehow triggers the body’s own immune system into a runaway inflammatory reaction, wherein, depending on the type of vasculitis, particular immune cells in particular regions of the body begin to react to their own inflammatory processes and by-products, no longer being dependent on the initial trigger to continue the process and no longer being able to recognise the cellular signals of “self” to draw a halt to the process.
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