title: Henoch-Schönlein purpura and systemic disease in children: retrospective study of clinical findings, histopathology and direct immunofluorescence in 34 paediatric patients.
abstract: BACKGROUND
  Henoch-Schönlein purpura (HSP), an IgA-mediated small vessel vasculitis, is the most common form of vasculitis in children. HSP is commonly associated with systemic involvement of the gastrointestinal tract, joints and kidneys. Renal involvement is the main cause of morbidity and mortality in HSP.
  
  
  OBJECTIVE
  To characterize the clinical, histopathological and direct immunofluorescence (DIF) findings, and to correlate the findings with systemic disease in 34 children with HSP seen at our institution.
  
  
  METHODS
  This was a retrospective review of paediatric patients with HSP and with available biopsy specimens seen at our institution between 1993 and 2013.
  
  
  RESULTS
  Thirty-four paediatric patients were identified (mean age 10·7 years). Renal involvement was found in 17 (50%) patients, gastrointestinal tract involvement in 22 (65%) and joint involvement in 23 (68%). Renal involvement was significantly associated with papillary dermal oedema on histopathology (P < 0·01) and the presence of perivascular C3 on DIF (P = 0·01). The presence of lesions above the waist was significantly associated with gastrointestinal involvement (P = 0·03), as was the presence of clinically apparent oedema (P = 0·01).
  
  
  CONCLUSIONS
  This study suggests that in children with HSP, microscopic dermal oedema and C3 on DIF may be predictive of renal involvement. Patients with clinically apparent oedema and lesions above the waist are more likely to have gastrointestinal involvement.
authors.affiliation: University of New Mexico School of Medicine, Albuquerque, NM, U.S.A.
authors.forename: E F
authors.initials: EF
authors.lastname: Johnson
authors.affiliation: Department of Dermatology, Mayo Clinic, Rochester, MN, U.S.A.|Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN, U.S.A.
authors.forename: J S
authors.initials: JS
authors.lastname: Lehman
authors.affiliation: Department of Dermatology, Mayo Clinic, Rochester, MN, U.S.A.
authors.forename: D A
authors.initials: DA
authors.lastname: Wetter
authors.affiliation: Division of Biomedical Statistics and Informatics, Mayo Clinic, Rochester, MN, U.S.A.
authors.forename: C M
authors.initials: CM
authors.lastname: Lohse
authors.affiliation: Department of Dermatology, Mayo Clinic, Rochester, MN, U.S.A.|Department of Pediatrics, Mayo Clinic, Rochester, MN, U.S.A.
authors.forename: M M
authors.initials: MM
authors.lastname: Tollefson
mesh_terms: D002648:Child; D004487:Edema / Q000209:etiology / Q000473:pathology; D005260:Female; D019085:Fluorescent Antibody Technique, Direct / Q000379:methods; D005767:Gastrointestinal Diseases / Q000209:etiology* / Q000473:pathology; D006801:Humans; D011695:IgA Vasculitis / Q000150:complications* / Q000473:pathology; D007592:Joint Diseases / Q000209:etiology* / Q000473:pathology; D007674:Kidney Diseases / Q000209:etiology* / Q000473:pathology; D008297:Male; D012189:Retrospective Studies