Visible Light Photopatch Testing of Common Photocontactants in Female Filipino Adults With and Without Melasma: A Cross-sectional Study.
Pua JM, Bautista D, Verallo-Rowell, VM,
Awarded Poster presentation at the WCD, Argentina, October 2007
Background: Sun exposure is a factor commonly associated with melasma, a pigmented dermatitis that may mimic Pigmented Photocontact Dermatitis, suggesting the possibility that Melasma may also be a photocontact dermatitis, for which photopatch testing can be diagnostic
Objective : To determine the results of Visible Light – photopatch testing in 30-55 year old Filipino adult femals, with and without melasma, majority of whom are exposed more to indoor Visible Light thatn outdoor sun exposure
Design : Cross – sectional study
Result : Fifty five percent of patines in the Melasma Group (N=11/20) has 29 (+) photopatch test reactions to visible light (11 Fragrances, 11 NACDG Photoallergens, 7 plant allergens). In the No Melasma Group, no patients had positive photopatch test reactions.
All the 29 positive photopatch test reactions were clinically relevant, establishing visible light phtocontact dermatitis to in 55% of patients in the melasma group.
There is a definite association with having a positive photopatch test and having melasma (P0.00 using two-tailed Fischer’s exact test). Among the subjects studied, a patient with a positive photopatch test has 12.67 time likelihood to develop melasma (P 0.05; 1,402-114) compared to those who had negative photopatch test results.
Conclusion : There is a definite association between melasma and the presence of visible light photocontact dermatitis. The Visible Light PCD more often found in melasma than in no-melasma patients may indicate that among sun-shy Asians, exposure to low energy Visible lights (from artificial light sources indoors) and common photocontactants, may induce a subclinical phototoxicity that over time appears as a pigmentary response, the melasma.