Henoch-Schonlein Purpura

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