title: Photopatch Testing in Chinese Patients Over 10 Years.
abstract: BACKGROUND
  Photoallergic contact dermatitis (PACD) is a hypersensitivity reaction that occurs when a previously photosensitized exogenous agent comes into contact with UV radiation. The best method for testing PACD is photopatch testing (PPT).
  
  
  OBJECTIVE
  The primary objective of the study was to determine the frequency of PACD to 20 different photoallergens in common usage in China during a 10-year period.
  
  
  METHODS
  All patients (n = 6153) who had PPTs done between 2005 and 2014 at the Department of Dermatology of Huashan Hospital, Fudan University, were included.
  
  
  RESULTS
  A total of 3767 PACD reactions in 3668 subjects (59.61%) were recorded. Of these allergens, chlorpromazine (CPZ) (51.82%), para-aminobenzoic acid (11.94%), thimerosal (9.81%), potassium dichromate (6.37%), sulfanilamide (5.38%), and formaldehyde (4.7%) were the top 6 allergens that elicited PACD reactions. A comparison of PACD reactions between January 2005 to December 2009 and January 2010 to December 2014 revealed a statistically significant decrease in PACD reaction for chlorpromazine, potassium dichromate, p-aminobenzoic acid, and p-phenylenediamine. Formaldehyde showed a trend toward a statistically significant increase in sensitization over the 10-year period.
  
  
  CONCLUSIONS
  In conclusion, positive PACD reactions were most frequent to chlorpromazine in our population. New allergens such as potassium dichromate and formaldehyde should be added to the test series.
authors.affiliation: From the Department of Dermatology, Huashan Hospital, Fudan University, Shanghai, China.
authors.forename: Yue
authors.initials: Y
authors.lastname: Hu
authors.forename: Duoqin
authors.initials: D
authors.lastname: Wang
authors.forename: Yanyun
authors.initials: Y
authors.lastname: Shen
authors.forename: Hui
authors.initials: H
authors.lastname: Tang
mesh_terms: D010129:4-Aminobenzoic Acid / Q000009:adverse effects; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000485:Allergens / Q000009:adverse effects*; D002648:Child; D002681:China / Q000453:epidemiology; D002746:Chlorpromazine / Q000009:adverse effects; D017454:Dermatitis, Photoallergic / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology*; D005260:Female; D005557:Formaldehyde / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D010328:Patch Tests; D011192:Potassium Dichromate / Q000009:adverse effects; D000077145:Sulfanilamide; D013424:Sulfanilamides / Q000009:adverse effects; D013849:Thimerosal / Q000009:adverse effects; D055815:Young Adult
chemical_list: D000485:Allergens; D013424:Sulfanilamides; D005557:Formaldehyde; D000077145:Sulfanilamide; D013849:Thimerosal; D011192:Potassium Dichromate; D010129:4-Aminobenzoic Acid; D002746:Chlorpromazine