title: Clinical and histopathologic review of Schnitzler syndrome: the Mayo Clinic experience (1972-2011).
abstract: BACKGROUND
  Schnitzler syndrome is a rare multisystem disorder, defined by urticaria and monoclonal gammopathy, that is associated with malignancy. Considered a neutrophilic urticarial dermatosis, previous reports have included patients with leukocytoclastic vasculitis.
  
  
  OBJECTIVE
  We sought to better define the clinical features, histopathology, and outcomes of Schnitzler syndrome.
  
  
  METHODS
  We retrospectively reviewed clinical records and cutaneous histopathology of all patients with Schnitzler syndrome seen at our institution from January 1, 1972, through July 31, 2011.
  
  
  RESULTS
  Of the 20 patients identified, 80% had IgM κ monoclonal gammopathy; others had IgG λ (10%), IgG κ (5%), or IgM κ+λ (5%). Patients had fevers (85%), arthralgias (70%), leukocytosis (70%), increased erythrocyte sedimentation rate (70%), bone pain (50%), lymphadenopathy (40%), and organomegaly (5%); 45% developed a hematologic malignancy. Histopathologic examination (n = 14) showed predominantly neutrophilic perivascular and interstitial inflammation (57%) or predominantly mononuclear cell perivascular inflammation (29%), with eosinophils in 50% of cases. None showed leukocytoclastic vasculitis.
  
  
  CONCLUSIONS
  Our study was limited by its retrospective design.
  
  
  CONCLUSIONS
  We added 20 patients to approximately 100 reported cases of Schnitzler syndrome. Neutrophilic urticarial dermatosis was the most common histopathologic pattern, but mononuclear cells were predominant in many cases and the infiltrates often contained eosinophils. A high index of suspicion and careful clinicopathologic correlation are needed to avoid diagnostic delays in this syndrome associated with hematologic malignancy.
authors.affiliation: Department of Dermatology, Mayo Clinic, Rochester, Minnesota 55905, USA.
authors.forename: Olayemi
authors.initials: O
authors.lastname: Sokumbi
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Drage
authors.forename: Margot S
authors.initials: MS
authors.lastname: Peters
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006761:Hospitals; D006801:Humans; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D019873:Schnitzler Syndrome / Q000175:diagnosis* / Q000473:pathology; D013997:Time Factors