Assessment of P16INK4A Expression in Oral Epithelial Dysplasia and Oral Squamous Cell Carcinoma and Its Correlation with the Histological Grade of the Tumour

Background: The objective of current study is to evaluate the role of HPV-16 in the pathogenesis of oral epithelial dysplasias (OED) and oral squamous cell carcinoma (OSCC) by immunohistochemistry (IHC) and to know whether HPV-16 participates in disruption of the regulation of p16 INK4A suppressor protein in OED and OSCC by IHC. Methodology: The present prospective study was done at Department of Pathology, ICARE Institute of Medical Sciences and Research and Dr. B.C.Roy Hospital, Haldia between the periods of December 2022 to May 2024 with a sample size of 130 cases after taking Institutional Ethics Committee approval. The following findings were noted down like demographic information, past and family history, history of present illness, and personal history. In clinical examination and type of the lesion (ulcerative, proliferative lesion, ulceroproliferative lesion, white patch and submucosal fibrosis) were noted. Biopsy samples obtained from patients with oral squamous cell carcinoma and premalignant lesions were fixed in 10% formalin within 30 minutes and for not more than 48 hours (ideal is 12-24 hours). It was then processed and embedded in paraffin wax according to the standard protocols. Thin section of 4 micron were cut and then stained with hematoxylin and eosin. The biopsy specimens were processed in the automated tissue processor for preparation of paraffin blocks as per standard guidelines. The tissue sections were stained routinely with Hematoxylin and Eosin stain as per standard guidelines. Paraffin blocks which were most representative of tumour tissue were chosen for performing immunohistochemistry IHC for p16. Results: Dysplastic lesions were more common in the age group of 41-50 years (43.6%) while the maximum number of cases (35.1%) S.C.C was in the age group of 51-60 years. Overall male predominance was in both oral dysplastic lesions (84.6%) and OSCC (73.6%). Male: Female ratio was 5.5:1 in dysplastic lesion and 2.8:1 S.C.C. Tongue was the most common site (46.1%) followed by buccal mucosa (43.6%) for dysplastic lesions and the most common site for S.C.C was buccal mucosa (39.5%) followed by tongue (26.4%).Majority of patients with dysplastic lesions presented with leukoplakia (79.5%0 followed by OSMF (10.3%) and maximum number of patients with S.C.C was growth in the oral cavity (60.4%) followed by ulcerative lesion (20.9%) and ulceroproliferative lesion (16.5%). Histopathology revealed maximum number of dysplastic lesions was mild dysplasia (41%) and well differentiated SCC (60%). The p16 positivity rate was 55.38%. Patients in the age group of 21-30 years showed 91.6% positivity. Below 50 years the p16 positivity was 77.7% and above 50 years the positivity was 69.5%.Thus the younger population showed more positivity for p16 than the older population. Conclusion: Diffuse pattern of 16 expressions was not seen in dysplastic lesion which ultimately helps to differentiate dysplastic lesion from malignancy. P16 proves to be of great help in diagnosing the histological grades in OSCC and dysplastic lesions which ultimately helps to rule out subjective variation in histological diagnosis.