Vasculitis

Vasculitis essentially means inflammation of blood vessels. This inflammation causes the lumen of the artery to become narrowed which in turn reduces or blocks blood supply downstream of the inflammation. The main symptoms and signs of vasculitis are due to the reduced blood supply to whichever organ or tissue is affected. e.g. If the artery to your foot is affected you may get gangrene of the foot. If the small arteries to the nerves are affected then you get nerve damage.

In some cases damage to the artery wall can cause it to weaken and to form aneurysms.  

Most types of vasculitis can cause severe organ damage or death if untreated.

Vasculitis can either be primary (which means it occurs without another known cause) or secondary (due to a known underlying disorder such as rheumatoid or lupus). In general, the different forms of primary vasculitis are classified by the predominant size of blood vessel involved and then sub classified by other associated manifestations.

The classification criteria for vasculitis is in the process of being updated by a study called DCVAS, which Dr Suppiah has been involved in.  Draft versions of the criteria have been presented at the American College of Rheumatology Annual Scientific Meeting in 2017 and 2018.  The final classification criteria are expected to be published in 2021.   


Large vessel vasculitis

The two main forms of primary large vessel vasculitis are Takayasu’s arteritis and giant cell arteritis.  These 2 forms of vasculitis affect the aortoa or its primary branches.

Takayasu's usually occurs in those <50 years of age and is more more common in Asia and the Middle East.  Giant cell arteritis effects the elderly, and is more common in in Caucasian populations.

Takayasu’s tends to cause loss of pulses and aching in limbs with activity whereas giant cell arteritis more commonly affects the head and neck arteries and causes headache, jaw pain when chewing and blindness.

Medium vessel vasculitis

The most common form of medium vessel vasculitis in adults is polyarteritis nodosa (PAN). PAN usually affects the renal arteries, gut arteries, and arteries supplying nerves and muscles (including the heart).   PAN is now a relatively rare disorder.  It was more common before routine vaccination for Hepatitis B.  Hep B was thought to be the cause in a large proportion of patients who developed PAN.  Recently a genetic conditions called the deficiency of adenosine deaminase 2 (DADA2) has been recognized as causing a certain proportion of PAN.  

Small vessel vasculitis

There are several different types of small vessel vasculitis. The most common group is associated with a blood test called anti neutrophil cytoplasmic antibody (ANCA). There are 3 distinct forms of vasculitis associated with ANCA. They include:
1) Granulomatosis with polyangiitis (GPA)
2) Microscopic polyangiitis (MPA)
3) Eosinophilic granulomatosis with polyangiitis (EGPA)

All these ANCA associated forms of vasculitis affect the smallest blood vessels in the body called capillaries. Common features include renal failure and severe bleeding in the lungs, but can affect any organ.  Untreated the mortality is >80% within 2 years which is higher than most cancers.  

GPA has other associated features such as chronic sinus symptoms, cavitating lung nodules, ear and nose cartilage inflammation and is associated with sub-type of ANCA called proteinase 3 (PR3).  MPA on the other hand does not have many non vasculitic manifestations and is associated with myeloperoxidase (MPO) ANCA.  EGPA is associated with asthma and raised levels of tissue and blood eosinophils (a type of white blood cell that is associated with allergy and parasitic infection).

Another relatively common form of small vessel vasculitis is IgA vasculitis which usually presents with a rash on the legs and buttocks, joint pain, abdominal pain and blood in the urine. 

Treatment

Most forms of vasculitis described on this page need prompt treatment to avoid permanent organ damage (e.g. blindness, kidney failure) or death. Treatment includes chemotherapy type medications such as cyclophosphamide or rituximab and high dose steroids to bring the disease under control (induction therapy), then other immunosuppressants to keep the vasculitis suppressed (maintenance therapy).


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