What is Systemic Vasculitis?

Vasculitis describes the inflammation of blood vessel walls in the body. Systemic vasculitis means that the inflammation is not specific to one size of blood vessel or to one organ of the body. Instead, any size of blood vessel of any organ can become inflamed.

Vasculitis Animation

Before reading all about systemic vasculitis and its’ different types, we recommend watching our informational animation which helps explain systemic vasculitis and its’ treatment. This is a helpful video that provides a way to visualize this disease, and can be found on our Vasculitis Animation page.

Types of blood vessel
vessel image

  • The three types of blood vessels are the arteries, veins, and capillaries.
  •  Arteries deliver oxygen-rich blood from the heart to the body. Arteries are further divided into three groups based on size: large, medium, and small. Most large arteries leave from the heart and gradually branch off into medium and small arteries.
  • The small arteries continue to branch into capillaries. Capillaries bring oxygenated blood in close contact with tissues and organs so that the oxygen leaves the blood and feeds the tissues/organs.
  • The capillaries carrying blood with no oxygen gradually come together and form the small veins. Like the arteries, veins also come in three sizes: small, medium, and large. The small veins come together to form medium veins, and medium veins come together to form large veins that carry blood to the heart.
    Inflammation can occur in the endothelial lining of the blood vessel or the blood vessel wall.


What is inflammation?
Inflammation occurs when the immune system identifies what it believes is a foreign substance in the body. In an attempt to remove the foreign substance from the tissue, the immune system sends immune cells to block off or degrade the substances. An accumulation of the immune cells in the tissue causes the tissue to swell. This swelling is known as inflammation. In vasculitis, immune cells accumulate in the vessel wall tissue. Some of the immune cells that accumulate also attempt to kill the blood vessel walls, leading to damage of the vessel. Often times, there is no foreign substance in the vessel wall, but the body wrongfully suspects that normal features on vessel walls are foreign.

Fates of inflamed vessels
Swelling of the blood vessel wall results in the narrowing of the space inside the vessel. This is called stenosis. If left untreated, the blood vessel walls can swell to the point of occlusion. This means that that the vessel walls are touching and there is no space for the blood to flow through the vessel.

Tissues and organs need to constantly be supplied by blood carrying essential oxygen and nutrients for the tissues/organs to function normally. Blood vessel occlusion is therefore dangerous because tissues/organs receive an inadequate blood supply. This condition is known as ischemia. Tissues left without oxygen and nutrients for a prolonged period of time may die (necrotize).

As mentioned earlier, vascular inflammation includes swelling as well as destruction of the vessels. Blood vessel walls that lose their elastic fibers become weaker and begin dilating. Dilation in one localized area is called an aneurism.
Some vessels may even become so weakened that they rupture. A ruptured artery cannot deliver blood to its destination. Ischemia and necrosis result in the tissues supplied by this vessel. Bleeding into the skin or other organs will result from a rupture.

In some cases, a thrombus can form. As a result of tissue destruction, the vessel wall may become sticky and


What symptoms does the child experience due to inflammation of the blood vessels?
Often times, when a child has systemic vasculitis, he/she will mostly experience inflammation in one size of vessel: large, medium or small. As we will see in Classifying Systemic Vasculitis, the size of the vessel affected, as well as other vessel factors, is used to diagnose a child with one of many forms of systemic vasculitis. Each type of vasculitis presents with its own specific group of signs, symptoms, blood test and imaging results. However, some general symptoms that are experiences by most vasculitis patients can be categorized based on the size of vessels affected.   

Constitutional symptoms present in almost all forms of systemic vasculitis: fever, fatigue, anorexia, weight loss, malaise.

  • Vasculitis of the large vessels
    The large vessels are the major highway carrying oxygen and nutrients to the organs of the body. When vasculitis affects these vessels, if the disease is left untreated for a long period, occlusions or thrombi can form. This is like a major roadblock on the highway that is stopping oxygen and nutrients from reaching the intended organ. Depending on the organ, the following symptoms can occur:

    • Vasculitis in artery feeding the brain can result in a stroke. Brain cells deprived of oxygen and nutrients begins to die. Depending on the region of the brain that the stroke occurs, patients can experience different focal neurological deficits.
    • Muscles – claudication (muscle pain) due to limited blood flow to muscles.
    • Kidney – hypertension (high blood pressure). If there is stenosis in the arteries leading to the kidneys, the kidneys will try to combat the reduced blood flow by increasing the blood pressure in the entire body.
  • Vasculitis of the medium vessels
    Medium blood vessels are the most likely to be severely weakened and injured from vasculitis. There is a risk of bleeding and severe fever.
  • Vasculitis of the small vessels
    Often accompanied by inflammation of surrounding tissue.
    Rupture and leakage from the small vessels commonly occurs. The symptoms depend on the location of the ruptured vessels.

    • Brain – referred to as a brain hemorrhage, the blood from the ruptured vessel leaks into surrounding tissue and causes brain cell death in that area (stroke).
    • Gut – bleeding from the small vessels shows as blood in the stool.
    • Kidney – the glomerulus are the small vessels in the kidneys where waste products are filtered out of the blood. Inflammation and damage of these vessels can lead to kidney failure.

Other Websites About Childhood Systemic Vasculitis

 If you would like to visit some more websites about systemic vasculitis in children, please feel free to visit some of the websites provided below:

  1. Printo.UK – Primary Systemic Vasculitis
  2. Boston Children’s Hospital – Vasculitis
  3. Vasculitis Foundation – Pediatrics/ Young Adults

Batu ED, Ozen S. Pediatric Vasculitis. Curr Rheumatol Rep, 2012. 14(2); p.121-129.
Covino JM, Hofmann-Ribowsky J. Vasculitis: diagnosis and treatment of blood vessel wall inflammation. JAAPA, 2012. 27(7); p.46-50.
Demirpolat G, Parildar M, Oran I, Aksu K, Memis A. Angiographic signs in specific vasculitides. Diagn Interv Radiol, 2008. 14(3); p. 159-162.