Contact and photocontact allergy in persistent light reactivity

Area of Science:

• Dermatology
• Photobiology
• Allergology

Background:

• Persistent light reactivity (PLR) affects elderly males.
• Patients with PLR exhibit adverse reactions to ultraviolet and longer wavelengths.
• Delayed-type hypersensitivity is a characteristic feature of PLR.

Purpose of the Study:

• To investigate the prevalence of contact and photocontact allergies in elderly males with PLR.
• To identify common allergens responsible for photoallergic reactions.
• To evaluate the diagnostic utility of histology in PLR.

Main Methods:

• Extensive phototesting with various wavelengths, including patch and photopatch testing.
• Comparison with a control group of 72 patients with chronic polymorphic light eruption.
• Histopathological examination of skin biopsies from 16 patients.

Main Results:

• 17 out of 18 PLR patients showed contact or photocontact reactions.
• Oak moss and lichen compounds were more common allergens than Compositae oleoresins.
• Histology supported clinical diagnosis in 13/16 biopsies but was not diagnostic alone.

Conclusions:

• PLR patients demonstrate a heightened susceptibility to delayed-type hypersensitivity and develop frequent photo and plain contact allergies.
• Allergies to oak moss, lichens, and cosmetic ingredients are prevalent.
• Light microscopy alone is insufficient for diagnosing PLR.