title: Urticarial pathology in Schnitzler's (hyper-IgM) syndrome.
abstract: BACKGROUND
  Schnitzler's syndrome is a rare disorder characterized by chronic urticaria and monoclonal IgM gammopathy. The mechanisms of the urticarial flares remain poorly understood.
  
  
  OBJECTIVE
  To more accurately define the histopathologic changes in urticarial lesions, we reviewed 25 original biopsies from 15 cases of Schnitzler's syndrome, 11 of which have previously been reported.
  
  
  RESULTS
  Thirteen specimens from 9 patients showed urticaria with neutrophils (neutrophilic urticaria). Necrotizing leukocytoclastic vasculitis with positive immunofluorescence studies was found only in 2 biopsies from 1 patient who was genetically deficient in C4. Five specimens showed lymphocytic urticaria. Four biopsies demonstrated a spongiotic dermatitis; an eosinophilic spongiosis was seen in 2 biopsies from a patient who later developed pemphigus vulgaris. Epidermal changes were seen in 17 specimens from 10 patients.
  
  
  CONCLUSIONS
  The histopathologic findings in Schnitzler's syndrome are not uniform although most cases demonstrated neutrophilic urticaria. Neutrophils in Schnitzler's syndrome are not usually related to immune complex vasculitis. Epidermal changes in Schnitzler's syndrome need to be further analyzed.
authors.affiliation: Department of Dermatology, Mayo Clinic Scottsdale, Ariz., USA.
authors.forename: F R
authors.initials: FR
authors.lastname: de Castro
authors.forename: I
authors.initials: I
authors.lastname: Masouyé
authors.forename: R K
authors.initials: RK
authors.lastname: Winkelmann
authors.forename: J H
authors.initials: JH
authors.lastname: Saurat
mesh_terms: D000911:Antibodies, Monoclonal; D001706:Biopsy; D002908:Chronic Disease; D003181:Complement C4 / Q000172:deficiency / Q000235:genetics; D003872:Dermatitis / Q000473:pathology; D004804:Eosinophils / Q000473:pathology; D004817:Epidermis / Q000473:pathology; D019085:Fluorescent Antibody Technique, Direct; D006801:Humans; D006942:Hypergammaglobulinemia / Q000473:pathology*; D007075:Immunoglobulin M; D008214:Lymphocytes / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009336:Necrosis; D009504:Neutrophils / Q000473:pathology; D010392:Pemphigus / Q000473:pathology; D013577:Syndrome; D014581:Urticaria / Q000473:pathology*; D018366:Vasculitis, Leukocytoclastic, Cutaneous / Q000473:pathology; D008258:Waldenstrom Macroglobulinemia / Q000473:pathology
chemical_list: D000911:Antibodies, Monoclonal; D003181:Complement C4; D007075:Immunoglobulin M