HPV-Negative Oral Squamous Cell Carcinoma Arising from Oral Submucous Fibrosis with p16INK4A Positivity and Cellular Senescence: A Case Report.

Background: Oral Submucous Fibrosis (OSF) is a chronic, progressive, and potentially malignant disorder primarily associated with areca nut chewing. While Oral Squamous Cell Carcinoma (OSCC) typically develops in the tongue and floor of the mouth, its occurrence in the buccal mucosa in the context of OSF is less common. The molecular mechanisms underlying OSF-associated OSCC remain unclear. p16INK4A is widely recognized as a surrogate marker for HPV-driven carcinogenesis; however, its role as an indicator of cellular senescence is increasingly acknowledged. Given that senescence contributes to various pathologies, including cancer, this case report explores its potential role in the pathogenesis of OSF-associated OSCC. Case Presentation: We present the case of a 39-year-old male with a 10-year history of gutkha chewing, who developed clinically advanced OSF and a well-differentiated OSCC of the buccal mucosa. Immunohistochemical (IHC) analysis revealed strong p16INK4A expression, increased p21WAF1/cip1 levels, and low Ki67 proliferative activity. Notably, Polymerase Chain Reaction (PCR) testing for HPV was negative. Further staining with SenTraGor (GL13) confirmed the presence of senescent cells, suggesting that p16INK4A overexpression in this case reflects cellular senescence rather than an HPV-driven oncogenic process. Conclusions: This case highlights the necessity of thorough molecular assessment when interpreting p16INK4A positivity in OSF-associated OSCC. The HPV-negative status, coupled with senescence markers, suggests that p16INK4A expression in such cases may show a senescence-associated tumorigenic pathway rather than HPV-mediated carcinogenesis. These findings support the inclusion of cellular senescence markers like SenTraGor in the diagnostic evaluation of OSCC arising from OSF.