There is a range of known vasculitic conditions, which can be classified according to the size of vessel affected. The clinical signs associated with vasculitis affecting different vessel sizes are shown in .
Clinical signs of vasculitis affecting different sized vessels.
HSP is a common type of small vessel vasculitis in the paediatric population. This is an IgA-mediated vasculitis often following on from an upper respiratory tract infection.1
It can affect multiple body systems and has a spectrum of severity, although in general it is a self-limiting process, which can be managed with symptom control and out-patient follow-up.
Far less common in this population is the condition Wegener's granulomatosis. This is also a multi-system vasculitic condition affecting small to medium vessels. It can affect any area of the body, including the upper and lower respiratory tract, kidneys, heart, joints, central nervous system and skin.1
The picture of organ involvement can vary widely between individuals. In two epidemiological population-based studies in England and Germany, the incidence rates for Wegener's granulomatosis were 10.6 and 6–12/million/year, respectively.2 3
The majority of cases were in those aged over 50 years.
In the paediatric population, Wegener's granulomatosis is extremely rare.4
For example, a tertiary referral children's hospital in Canada reported that only 25 cases had been managed there over a 21-year period up to 2005.5
Criteria set out by the Paediatric Rheumatology European Society and European League Against Rheumatism for diagnosing Wegener's granulomatosis in children is shown in box 1
Criteria for diagnosis of Wegener's granulomatosis in children as set out by the Paediatric Rheumatology European Society and European League Against Rheumatism. *If kidney biopsy is performed it characteristically shows necrotizing pauci-immune glomerulonephritis.
In trying to differentiate Wegener's granulomatosis from other vasculitic conditions, the ANCA test is particularly useful. The PR3-ANCA is highly sensitive and specific for Wegener's granulomatosis.7
The treatment of Wegener's granulomatosis generally involves immunosuppression. It will tend to fluctuate between periods of relapse and remission.
With the limited numbers of cases of Wegener's granulomatosis in the paediatric population, it remains uncertain what the long-term prognosis is.
- Beware of deteriorating renal function in ‘HSP’ with haematuria.
- Consider causes of vasculitis less common in the paediatric population.
- Wegener's granulomatosis is a small vessel vasculitis that can present with features similar to more benign conditions like HSP.
- Be open-minded and ready to reconsider the diagnosis made initially if the disease does not behave as expected.