What Are the Causes and Types of Vasculitis?
The causes of vasculitis diseases are largely unknown. Immunologic abnormalities (autoimmune disorders) seem to be the underlying cause for many vasculitic disorders, leading to inflammatory changes in the blood vessels walls.
Vasculitis diseases can involve certain blood vessel types or sizes. They may also involve certain organs. The most common classification system is based on blood vessel size.
Vasculitis affecting large blood vessels
Vasculitis affecting large blood vessels is called large vessel vasculitis and may include Takayasu arteritis and giant cell arteritis. Takayasu arteritis typically involves the aorta and its main branches. Giant cell arteritis or temporal arteritis generally affects the branches of the aorta that supply blood to the head.
Medium-vessel vasculitic disorders
Medium-vessel vasculitic disorders include polyarteritis nodosa (PAN), Kawasaki disease, and vasculitis of the central nervous system. PAN classically affects the medium- to small-sized arteries, and it mainly involves the vessels of the kidneys (renal vasculitis) and the gut. A variation of this condition may affect smaller vessels and is called microscopic polyangiitis or microscopic polyarteritis. Some association exists between hepatitis B infection and PAN.
Kawasaki disease is a type of medium- and small-vessel vasculitis affecting the arteries of the heart (coronary arteries) in children. It is associated with a generalized febrile infection, which can cause vasculitis of the heart in the convalescence period of the illness.
Vasculitis of the central nervous system (CNS vasculitis or cerebral vasculitis) is a rare disease characterized by inflammation of the arteries of the brain and the spinal cord. This condition may sometimes be associated with some viral infections, Hodgkin's disease, syphilis, and amphetamine use. In some instances, no underlying cause can be identified.
Small-vessel vasculitic diseases
There are several types of small-vessel vasculitic diseases. Churg-Strauss arteritis is an uncommon small-vessel disease which mainly affects the skin (cutaneous vasculitis) and the lung, although it rarely can involve other organs.
Wegener's granulomatosis is vasculitis of small arterioles and venules. It can affect many organs of the body (systemic vasculitis), but it usually involves the kidneys, the lungs (pulmonary vasculitis), and upper respiratory tract (nasal cavity and sinuses). Certain antibodies (antineutrophil cytoplasmic antibodies or ANCA) are associated with Wegener's disease and may be detected in the blood of these patients.
Henoch-Schonlein purpura is another small-vessel vasculitis which also affects many different organs (systemic vasculitis). This vasculitis is seen in infants, children, and adults, but it is more common in children between four to seven years of age.
Hypersensitivity vasculitis is the term used for types of small-vessel vasculitis that may be related to an allergic insult to blood vessels. The main areas of involvement of these conditions are cutaneous (affecting the skin) as they damage the small vessels of the skin, and, therefore, they may also be called predominantly cutaneous vasculitis or cutaneous leukocytoclastic vasculitis.
Essential cryoglobulinemia vasculitis is another type of rare small-vessel disease. Cryoglobulins are small protein complexes that can precipitate in cold temperatures. They may cause vascular inflammation by depositing in the vessel walls.
Some small-vessel vasculitis diseases can be related to an underlying rheumatologic disorder (connective tissue disorders), such as systemic lupus erythematosus (SLE) or lupus vasculitis, rheumatoid arthritis or rheumatoid vasculitis, Behcet's disease, or relapsing polychondritis. These conditions are typically confined to small vessels.
Small- and medium-vessel vasculitis can also be caused certain viruses. The most common viruses associated with vasculitis are hepatitis B, hepatitis C, human immunodeficiency virus (HIV), cytomegalovirus (CMV), Epstein-Barr virus, and parvovirus B19.