title: IgG4-positive plasma cells in cutaneous Rosai-Dorfman disease: an additional immunohistochemical feature and possible relationship to IgG4-related sclerosing disease.
abstract: BACKGROUND
  Cutaneous Rosai-Dorfman disease (CRDD) shares the histopathological features of abundant plasma cells and stromal fibrosis with IgG4-related sclerosing disease. The possible role of IgG4+ plasma cells in CRDD was investigated.
  
  
  METHODS
  Twelve cases of CRDD were reviewed, and their lesions were immunostained with anti-IgG4 and anti-IgG antibodies. The number of IgG4+ and IgG+ plasma cells and their ratios were estimated. Serum IgG4 and IgG concentrations were measured in two recent cases.
  
  
  RESULTS
  Many IgG4+ and IgG+ plasma cells were found in all 12 cases. IgG4+ plasma cells ranged from 21 to 204 per high-power field (HPF) (mean 117/HPF), and IgG+ plasma cells ranged from 114 to 759/HPF (mean 349/HPF). All cases had more than 30 IgG4+ cells/HPF, except one case. The IgG4/IgG ratio ranged from 16% to 51% (mean 34%). Serum IgG4 concentration and serum IgG4/IgG ratio were increased in one recent case. Various degrees of stromal fibrosis were present in all cases.
  
  
  CONCLUSIONS
  The presence of many IgG4+ plasma cells and stromal fibrosis suggests that CRDD may be related to IgG4-related sclerosing disease. Many IgG4+ plasma cells is another feature of CRDD, and serum IgG4 may be elevated.
authors.affiliation: Department of Pathology, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kwei San, Tao Yuan, Taiwan. ttkuo@adm.cgmh.org.tw
authors.forename: Tseng-tong
authors.initials: TT
authors.lastname: Kuo
authors.forename: Tse-Ching
authors.initials: TC
authors.lastname: Chen
authors.forename: Li-Yu
authors.initials: LY
authors.lastname: Lee
authors.forename: Pei-Hsuan
authors.initials: PH
authors.lastname: Lu
mesh_terms: D015618:Histiocytosis, Sinus / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology; D007150:Immunohistochemistry; D010950:Plasma Cells / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*; D012871:Skin Diseases / Q000276:immunology* / Q000378:metabolism / Q000473:pathology*
chemical_list: D007074:Immunoglobulin G