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BASICS

Description

  • Small vessel vasculitis with IgA immune complex deposition.
  • Multisystem: skin, joints, GI tract, kidneys.
  • Formerly known as Henoch-Schönlein purpura; increasingly termed immunoglobulin-A vasculitis (IgAV).
  • Self-limited in most cases, but renal damage causes morbidity and mortality.

Epidemiology

  • Annual incidence: 29.9/100,000 children; 0.1-1.8/100,000 adults.
  • Peak age: 4-6 years; 90% under 10 years.
  • Male predominance: M:F ratio ~1.2-1.8:1.
  • More common in Caucasians and Asians.
  • Seasonal: fall and winter predominance.

ETIOLOGY AND PATHOPHYSIOLOGY

  • Triggered by increased IgA1 production leading to immune complex deposition and complement activation.
  • Small vessel inflammation causes tissue necrosis and fibrosis in affected organs.
  • Likely multihit pathogenesis; infectious triggers common (URI prodrome).
  • Associated infections: Group A Streptococcus, parvovirus B19, Bartonella, Helicobacter pylori, adenovirus, others.
  • Drug triggers more common in adults (e.g., acetaminophen, ACEI/ARB, antibiotics, NSAIDs).
  • Rare vaccine associations reported.
  • Genetic predisposition: associations with α1-antitrypsin deficiency, familial Mediterranean fever, HLA subtypes, renin-angiotensin polymorphisms.

COMMONLY ASSOCIATED CONDITIONS

  • Rare associations with solid tumors, lymphomas, and other malignancies.
  • Possible links with H. pylori infection, immune disorders (food/drug allergies, IBD).

DIAGNOSIS

Clinical Criteria

  • Mandatory: palpable purpura without thrombocytopenia.
  • Plus at least one of:
  • Diffuse abdominal pain
  • Biopsy showing predominant IgA deposition
  • Arthralgia or arthritis
  • Renal involvement (hematuria or proteinuria)
  • Direct immunofluorescence for IgA may aid diagnosis.

History

  • Recent infection or drug exposure.
  • Rash: palpable, nonblanching purpura; typically symmetric on lower extremities/buttocks.
  • GI symptoms: abdominal pain, nausea, vomiting, GI bleeding.
  • Joint symptoms: symmetric polyarthritis, mainly knees and ankles.
  • Renal: hematuria, oliguria.
  • Rare: CNS symptoms, scrotal swelling/orchitis.

Physical Exam

  • Palpable purpura, petechiae, possible ecchymoses/bullae.
  • Abdominal tenderness; rectal exam for GI bleeding.
  • Joint tenderness without erythema or effusion.
  • Orchitis with scrotal swelling.
  • Hypertension with renal involvement.
  • Rare CNS or pulmonary findings.

Differential Diagnosis

  • Infectious: meningococcemia, Rocky Mountain spotted fever, bacterial endocarditis, EBV, sepsis.
  • Vasculitis: polyarteritis nodosa, granulomatosis with polyangiitis, lupus, Kawasaki disease.
  • Others: IBD, thrombocytopenic purpura, juvenile arthritis, leukemia, hereditary hemorrhagic telangiectasia, child abuse.

DIAGNOSTIC TESTS

Initial Labs

  • CBC: leukocytosis, thrombocytosis; eosinophilia common; thrombocytopenia suggests alternative diagnosis.
  • Blood cultures if sepsis suspected.
  • Renal function: serum chemistries, urinalysis for hematuria/proteinuria.
  • Coagulation studies: typically normal in HSP.
  • Inflammatory markers: ESR, CRP.
  • IgA levels: often elevated but nonspecific.
  • Complement levels: normal or decreased.
  • Antistreptolysin-O titer for recent streptococcal infection.

Imaging

  • Abdominal X-rays or ultrasound to assess for intussusception or GI complications.
  • CT angiography for GI bleeding localization if indicated.

Biopsy

  • Renal biopsy if diagnosis uncertain or severe nephritis.
  • Skin biopsy shows leukocytoclastic vasculitis with IgA deposition.

TREATMENT

General Measures

  • Supportive care: rest, elevation, hydration, nutrition.

Medications

  • Most cases self-limited; supportive care often sufficient.
  • NSAIDs for arthralgia (caution if renal involvement).
  • Corticosteroids:
  • For severe joint, abdominal pain, cerebral vasculitis, pulmonary hemorrhage, orchitis, or severe renal disease.
  • Oral prednisone 1-2 mg/kg/day or IV methylprednisolone pulses.
  • Early steroids may reduce symptom duration but do not prevent long-term renal involvement.
  • Immunosuppressants (cyclosporine, mycophenolate, cyclophosphamide, rituximab, plasmapheresis) for severe or steroid-resistant renal disease—clinical consensus lacking.

Adjunct Therapy

  • ACE inhibitors or ARBs for persistent proteinuria.

ISSUES FOR REFERRAL

  • Nephrology: for renal biopsy, nephrotic-range proteinuria, or persistent proteinuria >100 mg/mmol after 3 months.

INPATIENT CONSIDERATIONS

  • Admit for:
  • Severe abdominal pain, GI bleeding
  • Renal insufficiency
  • Altered mental status
  • Severe arthritis limiting mobility
  • Hypertension or nephrotic syndrome

ONGOING CARE

Follow-up

  • Weekly during acute illness: history, physical exam, BP, urinalysis.
  • Monthly for ≥6 months to monitor for renal involvement.
  • Monitor pregnant women for proteinuria and hypertension.
  • Evaluate for occult malignancy in adult-onset HSP.

PATIENT EDUCATION

  • Resources: National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC): IgAV.

PROGNOSIS

  • Dependent on renal involvement severity.
  • Usually self-limited: 94% children, 89% adults.
  • Most resolve in 4 weeks; recurrence rate ~33% within 6 months.
  • Poor prognostic factors: age >8 years, fever at presentation, purpura above waist, elevated ESR/IgA, severe renal histology.
  • Chronic renal disease in up to 20% children, 50% adults with nephritis.
  • Long-term renal failure risk ≤5%.

COMPLICATIONS

  • Nephrotic/nephritic syndrome, renal failure, hypertension.
  • GI: hemorrhage, intussusception, infarction, obstruction.
  • Pulmonary: alveolar hemorrhage.
  • CNS: cerebral hemorrhage, seizures.
  • Others: orchitis, testicular torsion, myocarditis, anterior uveitis.

CLINICAL PEARLS

  • Classic tetrad: palpable purpura, abdominal pain, arthralgia, renal involvement.
  • Supportive care mainstay; steroids for severe complications.
  • Close renal monitoring essential for all patients up to 6 months.

REFERENCES

  1. Pohl M. Henoch-Schönlein purpura nephritis. Pediatr Nephrol. 2015;30(2):245-252.

ADDITIONAL READING

  • Kawasaki Y. The pathogenesis and treatment of pediatric Henoch-Schönlein purpura nephritis. Clin Exp Nephrol. 2011;15(5):648-657.