Henoch-Schonlein Purpura (HSP)

Epidemiology

  • History: first described by Dr. William Heberden in London in 1801
    • Johann Schönlein (1837) and Edouard Henoch (1874) reported additional cases decades later
  • Predisposing Factors: preceding URI occurs in 66% of cases
  • Peak age: infancy/childhood (mean age: 5.9 y/o)
    • However, can occur at any age: generally more severe in adults
    • >90% of cases occur in children
  • Henoch-Schonlein Purpura is the most common form of vasculitis in children
  • Annual Incidence: 140 cases/million persons

Physiology

  • Hypersensitivity vasculitis (mostly involving the post-capillary venules within superficial dermis) with leukocytoclasis
  • Probably due to immune complex deposition in response to an infection
    • Probably due to IgA immune complexes

Pathology

  • Pathology with Diffuse Alveolar Hemorrhage: pulmonary capillaritis (see Wegener’s above)
  • IgA immune complexes have been seen in the alveolar septa

Diagnosis

  • Serology:
    • ANA: negative
    • Anti-DNA: negative
    • RF: negative
    • C3/C4/CH50: normal
    • ANCA: variable
    • Anti-GBM: negative
    • Immune complexes (with IgA): positive
  • PFT’s:
    • Decreased DLCO: in cases with interstitial infiltrates
    • Increased DLCO: during active diffuse alveolar hemorrhage
  • ABG: elevated A-a gradient
  • U/A: abnormal
  • CXR/CT Patterns
    • Pleural effusion
    • Diffuse or patchy perihilar/alveolar infiltrates: may be trasient
      -Interstitial infiltrates: may appear with chronic or recurrent diffuse alveolar hemorrhage
  • OLB: may be necessary
    • Tissue Ab staining: granular pattern (IgA) in alveolar septa
  • Skin Bx: diagnostic (IgA deposition)
  • Renal Bx: focal segmental necrotizing glomerulonephritis, crescents
    • IgA deposition
  • FOB:
    • BAL: RBC’s/ hemosiderin-laden macrophages

Clinical

Dermatologic Involvement

  • Lekocytoclastic Vasculitis: palpable purpura (of LE), nodules, ulcers

Renal Involvement

(only 5% of cases develop progressive chronic kidney disease)

  • Glomerulonephritis/Renal Failure
  • Hematuria

Pulmonary Involvement (rare)

  • Diffuse Alveolar Hemorrhage (see [[Diffuse Alveolar Hemorrhage]])
    • Hemoptysis
    • Cough
    • Dyspnea
    • Chest Pain
  • Lung Cancer (squamous cell) (see [[Lung Cancer]])

Rheumatologic Involvement

  • Polyarthralgias (without arthritis)

GI Involvement

  • Abdominal Pain

Treatment

  • NSAID’s: avoid in presence of renal and GI disease, as may excerbate these
  • Dapsone (100 mg/day) : may be effective
  • Corticosteroids: effective in treating joint and GI symptoms
    • Not effective in treating skin symptoms: skin symptoms usually resolve spontaneously though

Prognosis

  • Usually self-limited: resoledv within a few weeks
  • Recurrences occur in 33% of patients: recurrence usually develops within the first few months after resolution of the first episode

References

  • The American College of Rheumatology 1990 criteria for the classification of Henoch-Schönlein purpura. Arthritis Rheum. 1990 Aug;33(8):1114-21