Immunohistochemical characterization of the tumor immune microenvironment in laryngeal premalignancy: insights into early immune alterations in carcinogenesis

Laryngeal squamous cell carcinoma (LSCC) frequently arises from premalignant dysplastic lesions, yet reliable predictors of malignant transformation remain limited. This study investigates the immune microenvironment of laryngeal dysplasia and its association with progression to invasive carcinoma. We conducted a retrospective cohort study of 110 patients with histologically confirmed laryngeal dysplasia excised between 2009 and 2022, reclassified according to the 2022 WHO two‑tier system. Clinical data, including tobacco and alcohol exposure, were collected, and outcomes included recurrence, progression to invasive carcinoma, and cancer‑free survival. Immunohistochemistry and digital image analysis were used to quantify intraepithelial and stromal immune markers (CD3+, CD4+, CD8+, CD68+, CD163+, PD-L1). High-grade dysplasia represented 68% of cases, and 33% progressed to invasive carcinoma. Intraepithelial T-cell and macrophage densities did not differ significantly between progressing and non-progressing lesions, whereas stromal immune characteristics showed prognostic value. In multivariate analysis, alcohol exposure, dysplasia grade, stromal CD8 + density, and PD-L1 expression were independently associated with progression. Former drinkers showed a higher risk than lifelong abstainers, while high-grade dysplasia carried a fourfold increased risk relative to low-grade lesions. Higher stromal CD8 + infiltration and lower stromal PD-L1 expression correlated with progression, though with modest effect sizes. Digital immune profiling validated distinct stromal immune signatures associated with progression in laryngeal dysplasia. These findings suggest that malignant transformation depends not only on histological grade and alcohol exposure but also on subtle immune alterations, supporting integration of stromal immune markers with WHO grading to refine risk stratification and guide surveillance strategies.