Revisiting Contact Sensitization Among Patients With LPP/FFA: Cross-Sectional Findings From 55 Cases

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.

To assess the prevalence of delayed allergic reactions to commonly used topical agents in patients with LPP/FFA.

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.

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.

Patch test reactivity rates in LPP/FFA patients did not exceed those observed in the control group.