Résumé
CONTEXT: Proliferative verrucous leukoplakia (PVL) is a highly persistent and aggressive oral pre‑malignant lesion with an obscure etiopathogenesis and a malignant transformation rate of 85‑100%. AIMS: The aim of the present study is to assess the role of Ki‑67, p16, CD34, Bcl‑2, cyclooxygenase‑2 (COX‑2) in the spectrum of PVL to ascertain their role in its etiopathogenesis. SETTINGS AND DESIGN: A retrospective chart analysis was carried out on a series of seven confirmed cases of PVL, which were followed‑up for 2 years. SUBJECTS AND METHODS: Immunohistochemical appraisal of these cases was carried out by a panel of markers, related to cell proliferation, cell cycle regulation, angiogenesis, apoptosis and inflammation. The expression of these markers was correlated with patients’ clinicopathological profile. STATISTICAL ANALYSIS USED: The frequency distribution of the group data was analyzed. RESULTS: The latest labeling index of Ki‑67 in our cases ranged from 8.18 to 12.6. p16 was positive in 3/7 cases. Bcl‑2 expression was moderately positive in 2/7 cases. All cases were intensely positive for COX‑2 staining. Microvascular density assessed by CD34 staining ranged from 11 to 20/high power fields. One case which transformed into squamous cell carcinoma demonstrated increased Ki‑67, Bcl‑2, COX‑2, CD34 expression, but negative p16 and Bcl‑2 expression. CONCLUSIONS: Application of these markers in understanding the behavior of PVL suggests that an imbalance between the proliferation apoptosis dynamics of the lesion accompanied by an increase in inflammation and angiogenesis underlie the molecular pathogenesis of the PVL spectrum.
Résumé
Context: p53 tumor suppressor gene which is a frequent target for mutations in a high percentage of oral cancer is regarded as an early event in carcinogenesis. Aim: The role of p53 was assessed in potentially malignant oral disorders (PMOD) to ascertain its prognostic significance. Settings and Design: Retrospective case series analysis was carried out on 30 paraffin-embedded tissue blocks of confirmed oral leukoplakia with dysplasia. Materials and Methods: 10 cases of each of mild, moderate, and severe dysplasia were immunohistochemically analyzed for p53 expression. The intensity of staining, intracellular localization, and basal and/or suprabasal distribution were assessed. Statistics: The intensity of p53 staining and its distribution were analyzed by the Chi-square test. The intracellular localization of p53 in different grades of dysplasia was subjected to one way ANOVA. P<0.05 was considered significant. Results: 21/30 cases of epithelial dysplasia were positive for p53 immunopositivity. Intensity of p53 expression was strong in 12 cases and weak in 9 cases (P<0.05). p53 positivity was confined to basal cells in mild dysplasia, while severe dysplasia showed both basal and suprabasal staining (P<0.05). Nuclear and cytoplasmic staining between and within the groups were F=9.027 and F=6.465 respectively with high significance noted between mild dysplasia and severe dysplasia. Conclusions: Increased p53 expressivity and greater cellular localization with increase in the severity of dysplasia indicated a direct association between the degree of epithelial dysplasia and p53 accretion, which occurs as an early event in oral carcinogenesis.