Fentichlor photocontact dermatitis: a persistent enigma.

BACKGROUND: Fentichlor elicits high rates of positive photopatch test reactions despite its currently unknown clinical relevance. OBJECTIVES: The aims of this study were to provide a comprehensive review of fentichlor, to investigate the characteristics of patients with photosensitivity to fentichlor, and to explore the current uses of fentichlor. METHODS: A review of photopatch test studies involving fentichlor was performed. A retrospective chart review was conducted in patients with positive photopatch test reactions to fentichlor at our institution. Product inquiries were placed to manufacturers of fentichlor to elicit the current uses of fentichlor. RESULTS: In selected photopatch test studies, positive reactions to fentichlor occurred in 0.0% to 11.8% of subjects. We found that 25 companies distribute or manufacture fentichlor worldwide, which includes 2 companies that sell 25-kg drums of fentichlor. The most common current uses of fentichlor are in research, in high throughput screening, and in antibacterial and antifungal creams. CONCLUSIONS: Our review of selected photopatch test studies demonstrates that fentichlor remains a potent photosensitizing allergen worldwide. The bulk quantities of fentichlor available for sale and the current uses of fentichlor suggest that fentichlor may be currently incorporated into consumer products. We recommend that fentichlor remain in the standard series of photopatch test allergens.