Abstract
Background:
Lichen planopilaris (LPP) is an inflammatory disease results in scarring alopecia. Frontal fibrosing alopecia (FFA) is considered a variant due to similar histological features. A possible link has been suggested between exposure to various products and disease development, although research findings have been inconsistent.
Objective:
To assess the prevalence of delayed allergic reactions to commonly used topical agents in patients with LPP/FFA.
Methods:
A real-world observational study compared patch test results between LPP/FFA patients and a matched control group from routine clinical practice (2018–2023). Patch testing was conducted using the: European Baseline, Cosmetics, Hairdressing, and Sunscreen. The control group included patients without LPP/FFA underwent the same test panels.
Results:
A total of 23 patients with FFA, 32 patients with LPP, and 171 controls were evaluated. Positive reactions in the European Baseline Series occurred in 26% of FFA patients, compared to 37% in the LPP patients and 56% in the control group. Common allergens included nickel and fragrance mix I, but their prevalence did not exceed rates in the general Israeli population. LPP/FFA patients had fewer positive reactions to cosmetics, hair products, and sunscreens. No clinically relevant reactions were demonstrated in the study.
Conclusion:
Patch test reactivity rates in LPP/FFA patients did not exceed those observed in the control group.
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