A 20-year analysis of previous and emerging allergens that elicit photoallergic contact dermatitis

Retrospective chart reviews are periodically needed to update allergen series to detect changes in photoallergic contact dermatitis (PACD) over time.

We sought to evaluate photopatch test results during a 13-year period and extend the observations to 20 years.

A retrospective chart review was conducted in patients who were photopatch tested.

In all, 76 patients were evaluated. A total of 69 positive photopatch and 45 positive patch test reactions were detected in 30 and 23 patients, respectively. The frequencies of the positive photopatch test reactions were sunscreens 23.2%, antimicrobial agents 23.2%, medications 20.3%, fragrances 13%, plants and plant derivatives 11.6%, and pesticides 8.7%. Of the positive photopatch reactions to antimicrobial agents, 60% were caused by Fentichlor.

This study was a retrospective chart analysis, and the number of patients was small.

Sunscreens and antimicrobial agents were the most frequent allergens eliciting PACD, and there was a decrease in PACD caused by fragrances. The number of reactions to medications increased. This study also demonstrated that pesticides can be a cause of PACD. The detection of reactions to Fentichlor was unexpected and, although they have been attributed in some studies to cross-reactions to sulfanilamides and bithionol, such a robust association was not observed in this study. This study extends our experience of the changes in the allergens that elicit PACD to 20 years.