Henoch-Schonlein Purpura

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Henoch-Schonlein Purpura - click to enlarge

Henoch-Schonlein Purpura (HSP) is a systemic IgA Vasculitis.

  • First described in a book by Heberden in 1801
  • Further characterised later by Henoch and Schonlein


Related to IgA Nephropathy.


Contents

Incidence

  • Incidence = 15-20 per 100 000
  • Age: mostly 2-12 years old. Adults occasionally.
  • Sex: male:female 2:1
  • Ethnicity: slightly more common in white children

Aetiology

Precipitating cause is unknown. A large proportion of patients describe having a viral upper respiratory tract infection preceeding the onset of HSP symptoms.


IgA, C3 and Immune Complex deposition in small vessels. Symptoms derive from the tissues involved:

  • Skin
  • Gastro-intestinal tract
  • Joints
  • Kidneys
  • Connective tissue


Renal biopsy findings are identical to IgA Nephropathy, though children rather than young adults are affected and symptoms are systemic rather than predominatly affecting on the kidneys in IgA Nephropathy.


Clinical features

  • Purpuric rash (>95%)
    • classically buttocks + lower limbs.
    • may not be present at presentation
  • Abdominal pain (mesenteric oedema)
    • Consider Intussussception due to oedema
    • Also, perforation, bowel ischaemia, melaena, haematemesis, appendicitis, pancreatitis
  • Oedema
    • Peripheral oedema
    • Scrotal oedema - consider testicular torsion if painful
  • Arthralgia
    • particularly knees and ankles
    • may be unable to weight bear
  • Nephropathy (50% , moderate-severe in 10%. <1% result in end-stage renal failure)
    • proteinuria
    • Hypertension


Investigations

It is important to fully evaluate the extent of involvement (if any) of the kidneys:

  • Urea and electrolytes, Full blood count
  • Blood pressure
  • Urine dip for protein and microscopic haematuria
    • Monitor for Glomerulonephritis / nephritis
  • Renal Biopsy may occasionally be required: (crescenteric glomerulonephritis most commonly)

The severity of renal impairment is not usually proportional to the severity of other clinical signs.


Investigate the abdomen if indicated by the presentation to exclude pathology

  • Pain may be due to mesenteric oedema, but the oedema can also predispose to the pathology listed above.


Morbidity, Mortality and Prognosis

Renal impairment is the primary source of morbidity. Intra-abdominal pathology is also an important cause.

  • HSP resolved spontaneously in most children within 6 weeks.
  • <5% have chronic symptoms


Haematuria / Proteinuria present in ~ 50%

  • <1% result in end-stage renal failure
  • 10-20% may have recurrence


Management

Treatment is largely symptomatic until the condition resolves.

  • Analgesia
    • NSAIDS (caution with renal impairment)
    • Prednisolone: may improve symptoms, but no evidence for reducing the incidence of renal impairment.
    • Other immunosuppressants have been tried in various regimens.


Monitoring for renal impairment should be ongoing whilst the patient has signs of HSP and for a brief period following resolution.

  • Urine dipstick testing should continue at home
  • Blood pressure should be monitored at home for a short period (if it has otherwise always been normal)



References

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