Background/Epidemiology
- Most common vasculitis in children, although can be found in all ages (75% of cases <10) (incidence ~10-20/100,000)
- Younger children are less likely to have complications e.g. nephritis of abdomincal complications
- Commonly follows an infective episode (usually Group A β-haemolytic streptococcus) or vaccination
Pathology
- IgA complexes are deposited in small vessels in the skin, gut, kidney (identical to IgA nephropathy- showing focal/segmental proliferative glomerulonephritis) and joints
Clinical Presentation
- Skin- palpable purpuric rash is always present (part of diagnostic criteria)
- May precede or be preceded by other systemic symptoms
- Usually symmetrical over the extensor surfaces, lower limbs and buttocks, arms, face and ears but usually spares the trunk
- Can range from petechiae to large ecchymoses
- GI
- Colicky abdominal pain occurs in 50-75% of cases
- Vomiting and GI bleeding (either overt (rare- 2% of cases) or as faecal occult blood)
- Joints
- Many patients will have joint involvement; which may precede the onset of a rash in up to a quarter of patients
- Usually arthritis of the large joints of the lower limb (e.g. knees, ankle, hips) although can affect upper limbs
- Pain, swelling, decreased ROM; rarely causes any permanent damage
- Renal
- Occurs in between 20 and 60% of patients, can be 4-12 weeks after the initial rash and other symptoms
- A range of renal symptomology can occur in HSP, including haematuria, proteinuria, nephrotic syndrome, nephritis, renal impairment and hypertension
Diagnosis
- Palpable purpura + one of
- Diffuse abdominal pain
- Arthritis or arthralgia
- Renal involvement (any haematuria and/or proteinuria)
- Any biopsy showing predominant IgA deposition
Investigations
- Majority of cases are clinical diagnoses
- FBC, U&Es
- Urinalysis
- Renal biopsy may be indicated in patients with renal failure and nephritic syndrome
Management
- Most patients will just require supportive treatment
- Steroids may be useful in patients with severe renal involvement and severe abdominal pain
- Patients should be closely monitored for renal involvement and followed up for up to year for this
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