Erythema nodosum primarily affects small arteries and leads to tender red nodules in the skin. It is commonly caused by streptococcal infections, sarcoidosis, tuberculosis, fungous infections, ulcerative colitis and allergic reactions to many drugs, notably sulfa antibiotics and oral contraceptives.
Inflammation of medium-sized arteries, as exemplified by polyarteritis nodosa, a disease of unknown cause, produces symptoms (fever, abdominal pain, weakness, nerve malfunction, asthma, hypertension and kidney disorders) depending on the organ involved. The affliction may follow hepatitis, bacterial infections and drug hypersensitivity.
Giant-cell arteritis and Takayashu arteritis are examples of inflammation of large or major arteries. These disorders often lead to headache, blindness, stroke, weakness, stiffness and arthritis. Their cause is unknown.
Collagen vascular diseases (autoimmune disorders) are frequently the basis for vasculitis. Such diseases include lupus, rheumatoid arthritis and polymyositis. The diagnosis is usually made by biopsy, during which a small piece of tissue, ordinarily from an arterial wall, is removed and examined under a microscope.
Obviously, with so many causes of vasculitis, the therapy depends on the underlying disorder. Infection must be treated, and any drug suspected of causing the condition should be immediately discontinued. Vasculitis almost always affects the organ to which circulation is reduced because of the inflammation: typically, the eyes, brain, skin, intestine, liver and kidneys. Therefore, when possible, it's important to discover the basis of the affliction (infection, drug reaction or self-allergy), rather than merely giving a name to the symptoms.
Hence, your friend needs more than a diagnosis of vasculitis. This is a bit like saying someone has "pneumonia"; only by determining the agent causing the infection can doctors tailor-make therapy. So more information is needed.
As a general rule, prednisone (a type of cortisone) is the treatment of choice for vasculitis associated with autoimmune causes and for vascular inflammation that is NOT due to infection. In many cases, prednisone reduces symptoms with remarkable speed, thereby preventing progression of the vasculitis with all its attendant risks, such as stroke and kidney failure. The treatment may have to be continued for many months, or it may be needed for only a few days.
In either case, vasculitis is serious and can reflect a dangerous underlying disorder which is unsuspected.
Although patients with vasculitis can be monitored by their family physicians, specialists (such as rheumatologists) may be necessary to assess and evaluate the many potential complications of this disorder.