A. Presentation

1. Primarily children and young persons
2. Purpuric Rash in 100%
3. Joint pain 85% with swelling
4. Abdominal Pain: 70%
5. Bloody (Guaiac+) Stools: 55%
6. Subcutaneous edema: 50%
7. Fever: 50%
8. Hematuria 30-40% (renal dysfunction)
9. Intususception is not uncommon, especially with bloody stools

B. Laboratory [1,2]

1. Leukocytosis with Left Shift
2. ESR mildly increased but may be >80mm/hr
3. Immune complex formation; Complement levels decreased
4. Anemia - secondary to GI Bleeding, chronic inflammation, renal failure
5. Renal Involvement (>50% of patients) [1,3]
   1. Endocapillary proliferative glomerulonephritis
   2. IgA deposition always observed, usually with immune complexes
   3. Segmental necrotizing vasculitis

C. Pathogenesis

1. Leukocytoclastic vasculitis (compare with polyarteritis nodosa)
2. Has been called an allergic purpura
   1. Likely has an anaphylactoid etiology, probably some gut organism
   2. Possible that stimulating organisms in gut induces abnormal IgA synthesis
3. Serum IgA decreased with formation of IgA immune complexes
   1. Consider evaluating for IgA Rheumatoid Factor
   2. IgA is found in the kidney (similar to IgA nephropathy or Berger's Disease)
4. Inciting event: Bacteria (? streptococcus), virus, insect sting, drug allergy
5. Probably related to hypersensitivity vasculitis
6. HSP may be related to acute hemorrhagic edema of childhood (AHE) [4]
   1. Also called Finkelstein's Disease
   2. Leukocytoplastic vasculitis
   3. Occurs in children under 2 years of age
   4. Dramatic onset of purpuric rash and edema
   5. Greater dposition of IgM in AHE compared with HSP, where IgA predominantes
   6. Less gastrointestinal and renal involvement than classical HSP

D. Therapy

1. Supportive
   1. Stop any offending agents
   2. Maintain fluid status
   3. Monitor renal function, skin integrity, and other affected organs closely
   4. Non-steroidal inflammatory agents may reduce pain, but can increase hemorrhage and adversely affect the kidney
2. Glucocorticoids
   1. Indicated for severe purpura or renal involvement
   2. Oral prednisone begin at 0.5-1mg/kg/d in most patients
   3. Pulse methylprednisolone (SoluMedrol®) in severe disease (500mg-1000mg qd IV)
3. Azathioprine (Imuran®)
   1. Glucocorticoid-sparing agent
   2. Begin at 2 mg po qd and increase to maximum 4mg/kg po qd
4. High dose Immunoglobulin (IVIg) [5]
   1. 2gm/kg each month x 3 months IVIg and 6 months of IM Ig
   2. Protected patients from renal dysfunction (both proteinuria and azotemia)
   3. Well tolerated for severe IgA nephropathy
5. Resistant cases may respond slowly to cyclopsorin A; thalidomide may be considered

E. Prognosis [3]

1. Severe renal disease at presentation is risk for long term renal impairment
2. Women with mild renal disease at presentation have risk for long term renal dysfunction
3. Careful monitoring of renal function throughout life is important

References

1. Kassutto S and Wolf MA. 2003. NEJM. 349(6):597 (Case Discussion)
2. Harrington JT and Colvin RB. 1994. NEJM. 330(12):847 (Case Record)
3. Ronkainen J, Nuutinen M, Koshkimies O. 2002. Lancet. 360(9334):666
4. Gattorno M, Picco P, Vignola S, et al. 1999. Lancet. 353(9154):728
5. Rostoker G, Desvaux-Belghiti D, Pilatte Y, et al. 1994. Ann Intern Med. 120(6):476