title: A localized flare of dermatitis may render patch tests uninterpretable in some patients with recently controlled widespread dermatitis.
abstract: BACKGROUND
  Patch testing rarely is confounded by localized dermatitis induced in the area being tested (usually the back). Its occurrence renders the interpretation of patch tests impossible.
  
  
  OBJECTIVE
  To review our experience of the circumstances in which this phenomenon occurs during patch testing.
  
  
  METHODS
  We retrospectively reviewed patients with this phenomenon who underwent patch testing from January 1, 2002, through June 30, 2006.
  
  
  RESULTS
  Of the 3,569 patients tested, 12 (0.34% [9 men and 3 women]) had development of this phenomenon. All patients previously had recent widespread dermatitis that was suppressed temporarily with topical corticosteroids and wet dressings at the time of patch testing. The period between control of the dermatitis and the initiation of patch testing was less than 1 week for all patients. Three patients (25%) had recently discontinued therapy with systemic corticosteroids (less than 1 week earlier).
  
  
  CONCLUSIONS
  In patients with irritable skin either immediately after widespread dermatitis is controlled or after the cessation of systemic corticosteroid treatment, a flare of dermatitis induced by patch testing may render patch tests unreadable and therefore uninterpretable. To avoid this confounding occurrence, a waiting period between control of widespread dermatitis and initiation of patch testing is advised.
authors.affiliation: Department of Dermatology, Mayo Clinic, Rochester, MN 55905, USA.
authors.forename: Anna J
authors.initials: AJ
authors.lastname: Magembe
authors.forename: Mark D P
authors.initials: MD
authors.lastname: Davis
authors.forename: Donna M
authors.initials: DM
authors.lastname: Richardson
mesh_terms: D000328:Adult; D000368:Aged; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use; D003872:Dermatitis / Q000175:diagnosis* / Q000188:drug therapy; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010328:Patch Tests; D011241:Prednisone / Q000627:therapeutic use; D012189:Retrospective Studies
chemical_list: D000893:Anti-Inflammatory Agents; D011241:Prednisone