comparison of the expression of cytokeratin 6 and 16 in oral lichen planus, oral lichenoid lesions with dysplasia and oral squamous cell carcinoma

Introduction: oral lichen planus (olp) and oral lichenoid lesions (oll/olr) are chronic inflammatory disorders of the oral mucosa with potential malignant transformation. cytokeratins 6 and 16 (ck6, ck16) are markers of epithelial proliferation and have previously been reported to be elevated in inflammation, wound healing, and epithelial tumors. this study aimed to compare ck6 and ck16 mrna expression across reticular olp (rolp), erosive olp (eolp), oral lichenoid lesions with dysplasia (olr + d), oral squamous cell carcinoma (oscc), and healthy controls. materials and methods: a cross-sectional study was performed on 90 archived oral tissue specimens. mrna expression was quantified using qrt-pcr, and data were analyzed using δct, δδct, and fold-change values. statistical comparisons were made using one-sample t-tests and one-way anova. results: ck6 and ck16 expression were significantly altered in all lesion groups compared with controls (p < 0.001). fold‑change analysis showed a slight decrease in ck6 expression in rolp (0.63‑fold), followed by progressive increases in eolp (1.59‑fold), olr + d (1.85‑fold), and oscc (2.33‑fold). ck16 expression increased from rolp (1.36‑fold), eolp (1.47‑fold), and olr + d (2.00‑fold) to oscc (2.72‑fold). however, no statistically significant differences were observed among the lesion groups for either gene (ck6: p = 0.840; ck16: p = 0.946). conclusion: ck6 and ck16 expression increases along the spectrum of oral epithelial lesions but does not reliably distinguish inflammatory, dysplastic, and malignant lesions. these cytokeratins primarily reflect generalized inflammatory and reparative processes, and their interpretation should be integrated with histopathology, clinical findings, and additional molecular markers. keywords: lichen planus; oral lichenoid lesions; oral squamous cell carcinoma; epithelial dysplasia; cytokeratin.