title: Comparative analysis of rosacea and cutaneous lupus erythematosus: histopathologic features, T-cell subsets, and plasmacytoid dendritic cells.
abstract: BACKGROUND
  Distinction of rosacea and cutaneous lupus erythematosus (LE) can be challenging because of significant clinical and histologic overlap. A controlled study comparing these conditions is lacking.
  
  
  OBJECTIVE
  We compared the histologic features, T-cell subsets, and plasmacytoid dendritic cells in rosacea and LE.
  
  
  METHODS
  Biopsy specimens of rosacea (n = 27) and facial LE (n = 30) were retrospectively reviewed and reacted with Alcian blue and periodic acid-Schiff stains, and CD4, CD8, CD25, and CD123 immunostains.
  
  
  RESULTS
  LE demonstrates a lower CD4:CD8 ratio (1.74 vs 2.80, P = .0064), fewer CD4(+)CD25(+) regulatory T cells (13% vs 31%, P < .0001), and more CD123(+) plasmacytoid dendritic cells (18% vs 6%, P = .0137) than rosacea. The plasmacytoid dendritic cells in LE are more likely to form clusters (P = .0137) and comprise at least 20% of the infiltrate (P = .0340). Also associated with LE are follicular plugging (P = .0039), perineural lymphocytic infiltrate (P = .0211), abundant mucin deposition (P = .0031), and conspicuous basement membrane thickening (P = .0073), whereas Demodex infestation (P = .0064) and sebaceous hyperplasia (P = .0029) are significantly associated with rosacea.
  
  
  CONCLUSIONS
  Although statistically significant, the immunophenotypic differences are rather small and limited for routine use.
  
  
  CONCLUSIONS
  The infiltrates in rosacea and LE differ immunophenotypically, and may aid in their distinction in addition to conventional histologic examination.
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Theodore T
authors.initials: TT
authors.lastname: Brown
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Eun-Young K
authors.initials: EY
authors.lastname: Choi
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Dafydd G
authors.initials: DG
authors.lastname: Thomas
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, Michigan; Department of Dermatology, University of Michigan, Ann Arbor, Michigan.
authors.forename: Alexandra C
authors.initials: AC
authors.lastname: Hristov
authors.affiliation: Department of Pathology, University of Michigan, Ann Arbor, Michigan; Department of Dermatology, University of Michigan, Ann Arbor, Michigan. Electronic address: mpchan@med.umich.edu.
authors.forename: May P
authors.initials: MP
authors.lastname: Chan
mesh_terms: D000328:Adult; D003713:Dendritic Cells / Q000276:immunology / Q000473:pathology*; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D008178:Lupus Erythematosus, Cutaneous / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012189:Retrospective Studies; D012393:Rosacea / Q000276:immunology / Q000378:metabolism / Q000473:pathology*; D016176:T-Lymphocyte Subsets / Q000276:immunology / Q000473:pathology*
keywords: CD123; CD25; CD4:CD8 ratio; immunophenotype; lupus erythematosus; plasmacytoid dendritic cells; regulatory T cells; rosacea