title: Langerhans cell collections, but not eosinophils, are clues to a diagnosis of allergic contact dermatitis in appropriate skin biopsies.
abstract: BACKGROUND
  Langerhans cell collections (LCCs) and eosinophils are traditionally considered histologic clues to allergic contact dermatitis (ACD), but rigorous histologic analyses are limited. We correlated the presence of LCCs and eosinophils in skin biopsies with patch test results in patients evaluated for ACD.
  
  
  METHODS
  Charts of all patients patch tested and biopsied at one institution from 2011 to 2013 were reviewed. Biopsies had to have a diagnosis of either spongiotic dermatitis, psoriasiform dermatitis or mixed psoriasiform/spongiotic dermatitis. Various histologic parameters were assessed, including the presence of LCCs and number of eosinophils.
  
  
  METHODS
  A total of 68 biopsies met study criteria. Of these, 27 (40%) had ≥1 LCC. Twenty-one out of 27 (78%) with ≥1 LCC were patch test positive; 6 were patch test negative (22%). Of 41 cases with no LCCs, 23 were patch test positive (23/41, 56%) and 18 were patch test negative (18/41, 44%). LCCs were significantly more common in patch test positive patients (p = 0.046). Eosinophil count did not significantly differ in patch test positive and negative cases (p = 0.216).
  
  
  CONCLUSIONS
  LCCs are significantly more common in patch test positive cases. There were no differences with regards to presence of eosinophils between patch test positive and negative groups.
authors.affiliation: Department of Pathology, The Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Rosa
authors.affiliation: Department of Pathology, The Cleveland Clinic, Cleveland, OH, USA.|Department of Dermatology, The Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Anthony P
authors.initials: AP
authors.lastname: Fernandez
authors.affiliation: Department of Dermatology, The Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Alok
authors.initials: A
authors.lastname: Vij
authors.affiliation: Department of Dermatology, The Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Apra
authors.initials: A
authors.lastname: Sood
authors.affiliation: Department of Pathology, The Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Plesec
authors.affiliation: Department of Pathology, The Cleveland Clinic, Cleveland, OH, USA.|Department of Dermatology, The Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Wilma F
authors.initials: WF
authors.lastname: Bergfeld
authors.affiliation: Department of Pathology, The Cleveland Clinic, Cleveland, OH, USA.|Department of Dermatology, The Cleveland Clinic, Cleveland, OH, USA.
authors.forename: Steven D
authors.initials: SD
authors.lastname: Billings
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001706:Biopsy; D017449:Dermatitis, Allergic Contact / Q000175:diagnosis* / Q000473:pathology*; D004804:Eosinophils / Q000473:pathology; D005260:Female; D006801:Humans; D007801:Langerhans Cells / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D012867:Skin / Q000473:pathology*
keywords: Langerhans cells; allergic contact dermatitis; eosinophils; patch testing