Vasculitis, or blood vessel inflammation, can affect any part of the body and potentially cause major health complications. When capillaries near the skin are involved, the disease presents as an abnormal-looking rash that may be painful. Many different factors can contribute to the development of a vasculitis rash, including bacterial infections, autoimmune disorders, and medication use. Treatment depends on the severity of the condition and the underlying cause, but most rashes go away in a matter of weeks without special care. Topical and oral medications are needed in some cases to relieve uncomfortable symptoms and shorten the healing time of the rash.
A vasculitis rash can appear anywhere on the body, but it is most often seen on the legs and ankles. It can manifest in many different ways. Some rashes appear suddenly and are characterized by splotchy patches of dark red or purple skin. Others develop gradually over the course of several weeks and create brittle blisters and lesions on the skin. Most vasculitis rashes are not itchy, though they may cause skin to become very tender to the touch. Additional symptoms of fever, fatigue, numbness, and joint pain are possible signs of a body-wide vasculitis complication that needs to be addressed immediately at a hospital.
The exact causes of vasculitis are not well understood, and in many cases an underlying factor cannot be discovered. Bacteria and viruses that penetrate the skin can damage blood vessels near the surface. Allergic reactions to drugs, food, or environmental pathogens can lead to inflammation and weakening of capillaries as well. In addition, certain autoimmune conditions, such as rheumatoid arthritis, occasionally affect normal blood flow to the skin and cause blood vessel complications.
A doctor can usually diagnose a vasculitis rash based on the appearance alone. Blood tests are performed to screen for infections, autoimmune disorders, and other potential causes of symptoms. Additional blood work and diagnostic imaging scans may be needed if the doctor suspects that vasculitis may be present in other organs of the body. After confirming a diagnosis, the physician can explain the condition in detail and discuss different treatment options.
A vasculitis rash that does not appear to be related to an infection or another identifiable cause usually is treated conservatively. The doctor may simply suggest resting and elevating the affected leg as much as possible and applying a topical analgesic to relieve pain. The rash typically begins to resolve in a few weeks or months without causing health problems. Prescription antibiotics, anti-inflammatory drugs, or immune system suppressants are usually effective at clearing up rashes that are secondary to underlying conditions.