Abstract
Introduction: Odontogenic Keratocyst (OKC) is a developmental odontogenic cyst whereas ameloblastoma is a benign odontogenic epithelial tumour, and squamous cell carcinoma is a malignant epithelial neoplasm. Although OKC is classified as a cyst, its high proliferative potential and aggressive behaviour often lead to uncertainty regarding its neoplastic nature. Cellular proliferation can be assessed using Immunohistochemical (IHC) markers, among which Ki-67 is considered reliable as it is expressed in all active phases of the cell cycle (G1, S, G2, and M), making it an accurate indicator of proliferative activity.
Aim: To compare the Ki-67 Labelling Index (LI) of OKC, Follicular ameloblastoma, Well-Differentiated Oral Squamous Cell Carcinoma (WDOSCC) and normal oral mucosa.
Materials and Methods: The present cross-sectional study was conducted in Department of Oral Pathology, Pondicherry, Mahatma Gandhi Institute of Dental Science from June 2022 till June 2024 for a period of two years. The Study included histopathologically diagnosed, paraffin-embedded archival tissue blocks of OKC, Follicular Ameloblastoma, WDOSCC, and Normal Oral Mucosa, along with Fresh Biopsy Specimens of OKC, Follicular Ameloblastoma, WDOSCC, and Normal Oral Mucosa. A total of 48 Cases were included, comprising 12 Cases each of OKC without Inflammation (Group A), Follicular Ameloblastoma (Group B), WDOSCC (Group C), and Normal Oral Mucosa (Group D). Study was carried out using three microns paraffin embedded formalin fixed tissue sections which were stained immunohistochemically with Ki-67 antibody and its Labelling Index (LI) was evaluated by manual counting of 10 camera-captured hotspot areas at X200 magnification on zig-zag pattern to avoid repetition. The results were later evaluated statistically by IBM SPSS Version 20.0. Mean and Standard deviation (SD) were used to summarise the data. A p-value of <0.05 was considered as statistically significant difference. Statistical tests employed are tests of normality, Oneway Analysis of variance (ANOVA) and appropriate post-hoc tests were performed for pairwise comparisons between groups.
Results: All cases of WDOSCC and normal oral mucosa were Ki67 positive, whereas in contrast, positive expression was observed in 10 (83.3%) cases of OKC and 5 (41.7%) cases of Follicular Ameloblastoma. The mean labelling index of OKC was 17.13±10.40, Ameloblastoma was 2.14±2.97, of OSCC was 35.19±15.41, and of Normal oral mucosa was 19.29±4.09. Mean labelling index of WDOSCC was the highest followed by normal oral mucosa and OKC and the lowest in follicular ameloblastoma.
Conclusion: The study findings highlight distinct differences in cellular proliferation among oral lesions, supporting the aggressive nature of WDOSCC and the comparatively lower proliferative potential of follicular ameloblastoma. OKC and normal oral mucosa had almost similar Ki-67 LI.