Henoch Schonlein Purpura (HSP)
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Introduction

Henoch-Schonlein Purpura (HSP) is a vasculitis that most commonly occurs in children. It is the most common vasculitis of childhood, and typically presents in children aged between 2-8.
In at least 50% of cases there is a history of recent URTI.
It tends to only affect the small vessels, and typically presents with:
  • Palpable purpura – red / purple rash, typically on the legs
  • GI disturbance
  • Arthritis
  • Glomerulonephritis

Urinalysis is the only investigation required for diagnosis.

Most cases of HSP are self-limiting and mild and may need only symptomatic treatment. All patients need close follow-up (usually in the from of repeat urinalysis, for up to 12 months) to identify those with significant renal impairment – which is often asymptomatic, and develops weeks or months after the onset (and resolution) of the rash and other signs.

Epidemiology and Aetiology

  • M:F ratio – up to 2 : 1
  • 6-20 cases per 100 000 anuually
  • 90% of cases occurs in children
  • 50-90% of cases have a preceding URTI (studies vary)
  • Caucasians more likely to be affected than other races
  • Risk factors include
    • Recent infection – group A strep, mycoplasma, EBV
    • Vaccination
    • Drugs, allergens – including in food and to insect bites
  • Typically occurs in winter

Pathology

HSP is the result of deposition of IgA complexes in small arteries, and subsequent complement activation. The exact aetiology is unknown, but could be a bacterial, viral or environmental agent. Often follows a respiratory tract infection
  • Renal lesions tend to be focal, segmental, proliferative glomerulonephritis
  • PLATELETS are normal

Presentation

  • Palpable purpura –  50-75% – red/purple discolorations in the skin, often on the extensor surfaces of the feet, legs, arms, or sometimes on the buttocks. The rash may initially resemble urtricaria, but later becomes palpable. Most commonly seen on the buttocks extending dow the legs to the feet. Symmetrical.
  • GI disturbance – 50% – may include colicky abdominal pain, abdominal tenderness, melena 
    • Can cause intussusception (2-3% of patients) and bowel obstruction, GI haemorrhage, bowel ischaemia and perforation
  • Arthritis – including swelling of the joints – occurs in about 75% of patients
    • Typically large joints
    • Usually lower limbs
    • Usually no effusion, not warm or red
  • Glomerulonephritis – occurs in about 50% of patients, only 5% progress to renal failure
    • Haematuria
    • Proteinuria
    • RBC casts
    • Hypertension
    • Could meet the criteria for both nephritic syndrome (haematuria) and nephrotic syndrome (no haematuria)
    • Most commonly occurs in the first few weeks and months after the onset of the rash – and requires ongoing monitoring for 12 months (see Follow Up below)
  • Respiratory
    • May cause alveolar haemorrhage (rare) which will result in respiratory distress
  • Scrotal involvement – may appear like testicular torsion
  • Neurological involvement
  • There is usually no relationship between the severity of the rash or other symptoms, and the extent of renal involvement
Image showing appearance of Henoch-Schonlein Purpurs Rash
Henoch-Schonlein Purpurs Rash

Disease progression

Rashes typically occur over a period of days. There may be several sites that develop at different times.
  • Often relapsing / remitting – with episodes lasting an average around 4 weeks
  • About 20% of cases will result in end-stage renal failure
  • Prognosis is worse in adults than children

Diagnosis

Often clinical, in children with the typical rash. Urinalysis will show abnormalities in up to 50% of patients, and should always be performed, but is not diagnostic.
  • If hypertension or haematuria or significant proteinuria, then formal urine microscopy (for red cell casts) and urinary protein/creatinine ratio may be performed
  • Consider blood tests for urea and electrolytes as well as albumin
Diagnosis can also be confirmed with biopsy of skin lesion, which will shows IgA deposition in the walls of small arteries, but this is rarely required.

Renal biopsy is advisable if signs of renal disease
Other signs include:

  • ↑ESR
  • Proteinuria

Differentials

  • Idiopathic thrombocytopenia (ITP)
  • Leukaemias – can cause petechial rash and fever

Treatment

Essentially symptomatic
  • Don’t forget to rule out medication as a cause

Analgesia

  • Regular paracetamol (10mg/Kg QID)
  • Consider NSAIDs – e.g. ibuprofen 15mg/Kg TDS – if not contraindicated – e.g. in severe renal failure
Steroids are the mainstay of treatment, and provide symptomatic relief for joint pain / swelling, oedema and abdominal pain, but they do not affect disease outcome, and do not improve renal function.
  • e.g. Prednisolone 1-2mg/Kg daily. Wean dose once symptoms start to settle
  • In severe renal disease, IV immunosuppressants may be considered (e.g. cyclophosphamide + prednisolone), but this is rarely needed and there is no good evidence about the benefits
Indications for hospital admission:
  • Severe pain
  • Abdominal complications
  • Renal involvement
  • Neurological signs or symptoms

Complications

  • GI bleed – can be massive and life threatening
  • Chronic renal failure – 5% of patients
  • Acute renal failure – rare
    • Renal complications are more likely in older children and adults
  • Haemoptysis – rare

Prognosis

  • Most cases resolve within 4 weeks. Usually the rash is the last symptom to resolve
  • Joint pain usually subsides within 72 hours
  • Uncomplicated abdominal pain usually resolves within 48 hours
  • HSP recurs in up to 1/3 of patients – usually within 4 months
  • Renal complications usually develop within 6 months
  • Children <3 have the best prognosis and rarely have any complications

Follow up

  • If initial urinalysis on presentation is normal, or shows only microscopic haematuria, then repeat urinalysis and blood pressure:
    • Weekly for the first months
    • Every 2 weeks from week 5-12
    • Again at 6 months and 12 months
    • If any evidence of flare-up of disease (ANY signs or symptoms, including hypertension only) start again at week one plan
  • Refer to paediatrics / renal if:
    • Any hypertension
    • Any abnormal renal function (check if abnormal urinalysis)
    • Macroscopic haematuria for 5 days or more
    • Nephritic syndrome
    • Persistent proteinurea
  • If there are no signs at 12 months, no further follow-up is required
    • In some cases, renal complications don’t become apparent until after 10 years

References

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Dr Tom Leach

Dr Tom Leach MBChB DCH EMCert(ACEM) FRACGP currently works as a GP and an Emergency Department CMO in Australia. He is also a Clinical Associate Lecturer at the Australian National University, and is studying for a Masters of Sports Medicine at the University of Queensland. After graduating from his medical degree at the University of Manchester in 2011, Tom completed his Foundation Training at Bolton Royal Hospital, before moving to Australia in 2013. He started almostadoctor whilst a third year medical student in 2009. Read full bio

This Post Has One Comment

  1. Joseph 15th November 2020 Reply

    In the intro it says “In 50% of cases there is history of recent URTI” and then in aetiology it says “60-90% of cases have a preceding URTI”
    Beginning to wonder.

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