Clinicopathological Correlation of Immunohistochemical Markers, Serum Biomarkers, and Masticatory Muscle Activity With the Severity of Oral Submucous Fibrosis.

BACKGROUND: Oral submucous fibrosis (OSMF) is a chronic, progressive condition recognised for its potential to undergo malignant transformation. Molecular biomarkers and functional muscle alterations may help predict disease progression and risk of transformation to oral squamous cell carcinoma (OSCC). OBJECTIVE: To evaluate immunohistochemical (IHC) expression of p63, Ki-67, SOX2, and E-cadherin; correlate their expression with clinical and histological grades of OSMF; assess serum iron and protein levels; and analyse masticatory muscle thickness and electromyographic activity. METHODS: A cross-sectional study was conducted over 18 months, including 30 OSMF patients, five healthy controls, and five OSCC patients. Clinical grading (Mehrotra), histological grading (Khanna and Andrade), immunohistochemical expression of p63, Ki-67, SOX2, and E-cadherin markers, serum biochemical profiling, ultrasonographic measurement of muscle thickness, and needle electromyography were performed. RESULTS: E-cadherin expression showed a significant and gradual reduction from normal mucosa to OSMF and further to OSCC (p = 0.017), whereas p63, Ki-67, and SOX2 exhibited significant progressive increases across the same continuum (p < 0.001). However, none of these markers showed a statistically significant correlation with the clinical or histological grades of OSMF. Serum iron, ferritin, and total protein parameters did not exhibit significant associations with the clinical grade of OSMF. In contrast, ultrasonography revealed a significant decline in the thickness of the masseter, temporalis, and orbicularis oris muscles with advancing clinical grades of OSMF (p < 0.05), indicating progressive myofascial involvement. Electromyographic findings corroborated these observations, with a reduction in motor unit action potential duration in the masseter muscle across advanced grades, reflecting underlying myopathic changes associated with fibrosis. CONCLUSION: p63, Ki-67, SOX2, and E-cadherin demonstrate significant expression across normal mucosa, OSMF, and OSCC, supporting their role as markers of malignant transformation. However, these biomarkers do not reliably reflect disease severity within OSMF. Ultrasonographic and electromyography (EMG) assessments correlate with clinical progression and may serve as valuable adjuncts for early detection of muscle dysfunction in OSMF.