Henoch-Schönlein Purpura

Henoch-Schönlein purpura (HSP), also known as immunoglobulin A vasculitis, is an autoimmune small-vessel vasculitis that typically presents as a tetrad of abdominal pain, arthralgia, hematuria, and purpuric rash. The pathophysiology involves the deposition of IgA immune complexes in multiple vessels following a trigger (infection/environmental), and the symptoms depend on the tissues that are involved. The diagnosis is established clinically, but can be supported with laboratory studies and skin or kidney biopsy. Management is mostly supportive, but may involve steroids and immunosuppressants in more severe cases. Prognosis is usually excellent, but some patients may develop end-stage renal failure.

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Overview

Definition

Henoch-Schönlein purpura (HSP) is an immunoglobulin A (IgA)-mediated small-vessel vasculitis.

Epidemiology

  • Most common vasculitis in children
  • 90% of cases occur in children 3–15 years of age.
  • 20/100,000 in children versus 5/100,000 in adults
  • More prevalent in whites
  • Men > women (1.2–1.8:1)
  • Rare in the summer months

Etiology

  • Multifactorial: genetic susceptibility and environmental triggers
  • Autoimmune/antigenic secondary to preceding infection (respiratory or GI) in 75% of the cases:
    • Most common identifiable preceding infection: group A streptococcus (GAS)
    • Other infections: mononucleosis, hepatitis, Mycoplasma and Campylobacter infections, viral upper respiratory infections (URIs)
    • Possible association with preceding MMR vaccination
  • Can be preceded by insect bites
  • Possibly associated with IgA nephropathy (Berger’s disease)
  • Associated with Familial Mediterranean fever
  • Drug induced: 
    • Ampicillin/penicillin
    • Erythromycin
    • Quinidine/quinine
    • Losartan

Pathophysiology

  • A disease of immune-complex deposition
  • Deposition of IgA, C3, and fibrin in small vessels results in vasculitis.
  • Neutrophils and monocytes predominate within the inflammatory infiltrate.
  • Multiple antigenic targets have been proposed, but inconsistently identified.
  • Affects tissues supplied by small vessels: 
    • Skin
    • Kidneys
    • GI tract
    • Joints
    • CNS
  • Skin biopsy reveals leukocytoclastic vasculitis in the postcapillary venules.
  • Renal biopsy reveals immune-complex deposition in the mesangium.

Clinical Presentation

  • Classic tetrad:
    • Purpuric rash
    • Abdominal pain
    • Arthralgia
    • Renal disease/hematuria
  • Skin (95%–100%):
    • 1st presenting sign in about ¾ of patients
    • Usually begins with an erythematous macular rash
    • Progresses to non-painful palpable purpura (hallmark clinical sign)
    • Symmetrically distributed in gravity-dependent areas (legs, buttocks)
    • The rash may resolve and then reoccur.
  • GI (35%–85%):
    • Nausea, vomiting
    • Colicky abdominal pain 
    • Bloody or non-bloody diarrhea
    • Complications: intussusception (ileo-ileal > ileocecal)
    • Most common GI complication in children, rare in adults
  • Arthralgia/arthritis (60%–85%):
    • Transient
    • Migratory
    • Swollen and tender joints
    • May affect 1–2 joints, mainly knee and ankle
    • Nonchronic, non-deforming
  • Renal (20%–54%):
    • Hematuria (ranging from microscopic to gross) is the most common finding.
    • Proteinuria (ranging from mild to nephrotic range):
      • Severe proteinuria is uncommon.
      • Signifies development of progressive disease
    • Hypertension
    • Possible progression to chronic renal disease, especially in adults
  • Others:
    • Scrotal pain/edema (2%–38%)
    • Subcutaneous edema
    • Encephalopathy
    • Keratitis/uveitis

Diagnosis

History and physical exam

  • Usually sufficient to establish diagnosis
  • URI/strep A prodrome followed by tetrad:
    • Rash
    • Abdominal pain
    • Arthralgia
    • Renal disease

Laboratory workup

Laboratory workup is used to rule out differentials and evaluate complications.

  • CBC: 
    • Normal RBC count or normocytic anemia (due to GI bleeding)
    • Normal platelet count or thrombocytosis
  • Chemistry:
    • Elevated BUN and creatinine
    • Electrolyte disturbance
  • Prothrombin/partial thromboplastin time:
    • Should be normal in HSP
    • Abnormalities should raise the suspicion of alternative diagnoses
  • Acute-phase reactants:
    • Elevated CRP
    • Elevated erythrocyte sedimentation rate (ESR)
  • IgA: increased (50%)
  • C3/C4: reduced
  • Factor XIII: reduced (50%)
  • Urine Analysis (UA): 
    • Hematuria (ranges from microscopic to gross)
    • Proteinuria (ranges from mild to nephrotic range)

Biopsy

  • Reserved for unusual/severe presentations
  • More commonly needed in adult patients
  • Skin: leukocytoclastic vasculitis in postcapillary venules
  • Renal biopsy reveals immune-complex deposition in the mesangium
HSP renal biopsy showing immunostaining for IgA

Renal biopsy in Henoch-Schönlein purpura showing immunostaining for IgA

Image: “Henoch-Schönlein nephritis IgA immunostaining” by Lazarus Karamadoukis, Linmarie Ludeman, and Anthony J Williams. License: CC BY 2.0

Imaging

Imaging is used for complicated presentations.

  • Ultrasound: 
    • To evaluate scrotal edema
    • To evaluate for intussusception (may show “target sign”)
  • Abdominal X-ray: to evaluate for intestinal obstruction
  • MRI/CT head: for neurological symptoms (small vessels)
Target sign typical of intussusception on abdominal ultrasound

Target sign typical of intussusception on abdominal ultrasound

Image: “Pelvic plastron secondary to acute appendicitis in a child presented as appendiceal intussusception. A case report” by Christianakis E, Sakelaropoulos A, Papantzimas C, Pitiakoudis M, Filippou G, Filippou D, Rizos S, Paschalidis N. License: CC BY 2.0

Management

Management

  • Supportive treatment (the only measure needed in mild cases):
    • Rest: bedrest with extremity elevation
    • Hydration
    • Analgesics:
      • Acetaminophen
      • NSAIDs
  • Renal involvement:
    • Observation with UA, and measurement of BP weekly for 6 weeks and monthly for 6 months:
      • Observe for hematuria
      • Observe for proteinuria
    • Antihypertensives, if needed
    • Corticosteroids, if persistent nephritic syndrome
    • Immunosuppressants
    • Plasmapheresis (delays progression)
    • End-stage renal disease: kidney transplant
  • Abdominal:
    • Corticosteroids for severe abdominal pain
    • Surgery for intussusception/bowel ischemia
  • CNS: immunosuppressants/corticosteroids
  • Arthralgia: corticosteroids for severe joint pain

Prognosis

  • Excellent prognosis if:
    • Mild renal symptoms
    • No CNS involvement
    • < 3 years of age
    • Duration < 6 weeks
  • Morbidity and mortality increase in the following cases:
    • Recurrent rash in 6 months
    • Severe renal symptoms
    • Adults
  • ⅔ of cases experience no recurrence.

Differential Diagnosis

  • Acute glomerulonephritis: an immune-mediated inflammation of the glomeruli. Causes involve primary and secondary inflammation and often follow a streptococcal infection. Acute glomerulonephritis presents with generalized edema, hypertension, and dark urine. Diagnosis is based on UA, blood work, and positive streptococcal cultures/titers. Management is mostly supportive.
  • Berger’s disease (IgA nephropathy): the most common cause of primary glomerulonephritis worldwide, which presents with IgA deposition in the mesangial tissues. A differentiating factor from HSP is the lack of extra-renal manifestations. Definitive diagnosis is based on renal biopsy. Management includes steroids and immunosuppressants.
  • Idiopathic thrombocytopenic purpura: immune-mediated destruction of platelets, which also presents with a purpuric rash. The differentiating factor is that HSP often results in thrombocytosis. Diagnosis is based on clinical presentation and low platelet counts. Management includes steroids and splenectomy in certain cases.
  • Meningitis in children: Neisseria meningiditis infections present with a similar rash that is non-blanching and associated with high-grade fever. Diagnosis is established with CSF Gram stain and culture, and the treatment is with antibiotics.
  • Infective endocarditis: inflammation of the endocardium secondary to infection. Infective endocarditis is associated with a skin rash similar to that seen in HSP. Diagnosis is established with blood cultures and echocardiogram. Antibiotics are the mainstay of treatment.

References

  1. Dedeoglu, F., Kim, S. (2019). IgA vasculitis (Henoch-Schönlein purpura): Clinical manifestations and diagnosis. Retrieved March 2, 2021, from https://www.uptodate.com/contents/iga-vasculitis-henoch-schonlein-purpura-clinical-manifestations-and-diagnosis
  2. Dedeoglu, F., Kim, S. (2021). IgA vasculitis (Henoch-Schönlein purpura): Management. Retrieved March 2, 2021, from https://www.uptodate.com/contents/iga-vasculitis-henoch-schonlein-purpura-management
  3. Bhimma, R. (2021). Henoch-Schönlein purpura (IgA vasculitis). Retrieved March 2, 2021, from https://emedicine.medscape.com/article/984105-overview
  4. Leung, A.K.C., Barankin, B., Leong, K.F. (2020). Henoch-Schönlein purpura in children: An updated review. Curr Pediatr Rev: 16(4),265–276. https://pubmed.ncbi.nlm.nih.gov/32384035/

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