title: Noninvasive evaluation of allergic and irritant contact dermatitis by in vivo reflectance confocal microscopy.
abstract: BACKGROUND
  The clinical differentiation of allergic contact dermatitis (ACD) and irritant contact dermatitis (ICD) is often difficult to accomplish. Reflectance-mode confocal microscopy (RCM) is an imaging technique that has previously been used to examine ACD and ICD noninvasively in vivo.
  
  
  OBJECTIVE
  To determine characteristic features of ACD and ICD and their kinetic evolution over time. Ethnic susceptibility to contact irritants such as sodium lauryl sulfate and Ivory dishwashing liquid was evaluated noninvasively, and the sensitivity and specificity of RCM parameters were analyzed in a clinical context and in reference to patch testing.
  
  
  METHODS
  Subjects were patch-tested with allergens, irritants, and controls. Clinical scoring and RCM evaluation were performed at various time points, assessing stratum corneum (SC) disruption, spongiosis, exocytosis, vesicle formation, and epidermal thickness.
  
  
  RESULTS
  RCM features of both ACD and ICD include spongiosis, exocytosis, vesicle formation, and blood vessel dilatation. SC disruption, epidermal necrosis, and hyperproliferation are hallmarks of ICD whereas ACD more typically presents with vesicle formation. Patients with ICD showed a more rapid recovery than those with ACD. When tested with Ivory soap at selected concentrations, Caucasians, when compared to African Americans, showed significantly lower clinical thresholds for ICD and features that were more severe.
  
  
  CONCLUSIONS
  RCM may be a promising new technology for longitudinal noninvasive studies of contact dermatitis (CD). Using a diagnostic algorithm and those parameters with high sensitivity for CD, RCM may facilitate the differentiation of acute ACD and ICD. RCM can reliably visualize cutaneous changes at subclinical degrees of CD, which suggests a possible role for RCM as an adjunctive tool in CD diagnosis. The results of this pilot study also indicate ethnic differences in the response to contact irritants. However, further studies are needed to substantiate the relevance and clinical applicability of our findings.
authors.affiliation: Department of Dermatology, Massachusetts General Hospital, Harvard Medical School, Boston, USA.
authors.forename: Susanne
authors.initials: S
authors.lastname: Astner
authors.forename: Salvador
authors.initials: S
authors.lastname: González
authors.forename: Ernesto
authors.initials: E
authors.lastname: Gonzalez
mesh_terms: D000328:Adult; D001741:Black or African American; D000368:Aged; D017449:Dermatitis, Allergic Contact / Q000473:pathology* / Q000503:physiopathology; D017453:Dermatitis, Irritant / Q000208:ethnology* / Q000473:pathology* / Q000503:physiopathology; D004198:Disease Susceptibility / Q000208:ethnology; D006801:Humans; D018613:Microscopy, Confocal; D008875:Middle Aged; D010328:Patch Tests; D012680:Sensitivity and Specificity; D044465:White People