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	Classification of vasculitic syndromes		Diagnosis
	Investigations		Treatment
	When using cyclophosphamide		Maintenance
	During remission		Adverse-effects
	Prophylaxis

Vasculitis is inflammation and necrosis of the blood-vessel wall with luminal thrombosis and distal infarction. Classification of vasculitic syndromes currently depends on clinical, histological and serological features at presentation.

		Vasculitis may be localised (limited to one organ, typically the skin, without vital organ damage or constitutional symptoms) or systemic (involvement of a vital organ or multiple organs with constitutional symptoms).
		Primary systemic vasculitis is assumed to be auto-immune in origin, secondary systemic vasculitis may accompany chronic infection, malignancy or other auto-immune disease: eg, systemic lupus erythematosis or rheumatoid arthritis. Systemic vasculitis is subclassified according to the size of the predominant blood vessel involved and the presence or absence of ANCA (Table 1).
		Vasculitis subgroups associated with ANCA have vasculitis predominantly involving microscopic vessels, and immune deposits are absent.

Rapidly progressive glomerulonephritis* is the renal manifestation of vasculitis. It has been classified according to serological features and renal immunofluorescence findings that are of direct relevance to its pathogenesis (Table 2)

The incidence of primary systemic vasculitis is 20-40/million population/year with 10-15/million/year having renal vasculitis. The incidence increases with age and the peak incidence is in the decades between 60 to 80 years of age.

Two year survival is 75% to 90%, with age and renal function being major predictors of outcome. Between 20 and 30% of those presenting with renal involvement progress to end-stage renal failure.

Diagnosis

History should consider prodromal features, usually of three to 12 months duration such as:

		polymyalgia
		weight loss;
		fevers and sweats; and rash.
It should also consider precipitating factors such as:
		drugs (hydralazine, propyl thiouracil and penicillamine);
		occupational exposure to toxic substances;
		immunisations;
		infections; and
		family history.

Examination should include careful examination for purpura, nail fold infarcts, endocarditis*, respiratory-tract disease and fundoscopy.

Investigations can be divided into evaluation of organ involvement and of immunological abnormalities. Chronic viral infection (with hepatitis B, C and HIV) needs to be excluded.

		ANCA testing should include Indirect Immunofluorescence (IIF) and PR3-ANCA and MPO-ANCA ELISAs.
		Positivity by IIF (C-ANCA or P-ANCA) alone, or by ELISA alone, has a specificity for vasculitis of 50-70% (less for P-ANCA).
		Positivity in both assay systems, typically but not exclusively, C-ANCA + PR3-ANCA or P-ANCA + MPO-ANCA has a specificity of over 90% for a diagnosis of systemic vasculitis.
		A negative ANCA does not exclude the diagnosis and occurs in 10-15% of new cases of systemic vasculitis affecting small vessels without immune deposits.

Diagnosis rests on the triad of:

		clinical presentation;
		serology; and
		histology.

Histology should always be sought if at all possible. Important mimics of vasculitis to be excluded include:

		endocarditis;
		athero-embolism;
		anti-phospholipid syndrome; and
		chronic infections -- such as, tuberculosis and fungi.