Unraveling the role of IL-17 in lichen planusTolušić Levak, Maja (Avtor) Pauzar, Mirta (Avtor) Plužarić, Vera (Avtor) Francesch, Nika (Avtor) Pauzar, Biljana (Avtor) Rajc, Jasmina (Avtor) Delaš Aždajić, Marija (Avtor) Mihalj, Martina (Avtor) inflammatory dermatoseslichen planusinterleukin-17immunoexpressionIntroduction: Lichen planus (LP) is a chronic T cell–mediated inflammatory disease affecting the skin and mucosa. Interleukin-17 (IL-17), a pro-inflammatory cytokine, has been implicated in LP pathogenesis, but its tissue-level expression across clinical variants remains underexplored. This study compares IL-17 expression in healthy skin and LP lesions and assesses variations based on clinical presentation. Methods: This cross-sectional retrospective study included 20 LP skin samples and 10 healthy controls. The sample collection spanned a period of 10 years. IL-17 expression was assessed via immunohistochemistry and quantified using a modified Q score. Samples were categorized by mucosal involvement and lesion distribution. Statistical analysis was performed with the MannWhitney U test. Results: IL-17 was absent in healthy skin but present in all LP samples. IL-17 expression was significantly higher in patients with both skin and oral mucosal involvement compared to those with cutaneous LP (p = 0.003). No significant difference was observed between generalized and localized LP. Conclusions: The results indicate a distinct increase in IL-17 expression in LP lesions, particularly with mucosal involvement, supporting its role in LP pathogenesis. These findings suggest IL-17 as a potential biomarker and therapeutic target, warranting further investigation in larger cohorts.20252026-06-09 08:38:04Neznano29904sl