Evaluation of Immunohistochemical Marker Bcl-2 in Epithelial Dysplasia and Squamous Cell Carcinoma of the Oral Cavity.

Abstract

Squamous cell carcinoma of the oral cavity is the most common malignancy noted globally.Pathogenesis of premalignant and malignant oral lesions is mainly attributed to the alteration in the molecular mechanisms that regulate apoptosis and cell proliferation. B-cell lymphoma gene 2 (Bcl-2) is the anti-apoptotic gene that prolongs cell survival by inhibiting apoptosis and is associated with the aggressive behaviour of malignant tumours. The aim of the study was to evaluate Bcl-2 expression in oral squamous cell carcinoma and dysplastic lesions of the oral cavity and to compare its expression with various grades of dysplasia and carcinoma. A hospital-based cross-sectional study was done on 80 clinically suspected cases of dysplastic and malignant oral cavity lesions received in the histopathology section of the Department of Pathology of Shri BM Patil Medical College Hospital and Research Center, Vijaypura, Karnataka. Out of 80 cases, 40 were squamous cell carcinoma, and 40 were dysplastic lesions of the oral cavity. For each case, two sections measuring 4 μm thickness were prepared. Hematoxylin and eosin staining was performed on one section, and Bcl-2 IHC staining was performed on another. Bcl-2 expression evaluation was done for each case of oral epithelial dysplasia and squamous cell carcinoma. Out of 40 cases of squamous cell carcinoma, 15 were well-differentiated, 22 were moderately differentiated, and three were poorly differentiated. In well-differentiated oral squamous cell carcinoma, Bcl-2 positivity was grade 0 in 66.7% of cases and grade 1 in 33.3% of cases. In moderately differentiated oral squamous cell carcinoma, Bcl-2 positivity was grade 1 in 63.6% of cases and grade 2 in 36.4% of cases. In poorly differentiated oral squamous cell carcinoma, Bcl-2 positivity was grade 1 in 33.3% and grade 2 in 66.7% of cases. Out of 40 cases of dysplastic lesions, 11 cases showed severe dysplasia, 11 cases showed moderate dysplasia and 18 cases showed mild dysplasia. grade 2 positivity was seen in 72.7% of cases of severe dysplasia and 63.6 % of cases of moderate dysplasia. In mild dysplasia, all of the cases showed grade 0 Bcl-2 expression. In poorly differentiated oral squamous cell carcinoma Bcl-2 positivity was high and low in well-differentiated oral squamous cell carcinoma. Bcl-2 expression was higher in severe dysplasia compared to moderate dysplasia, which may indicate aggressive behaviour of tumour in poorly differentiated oral squamous cell carcinoma and severe dysplasia.