Role of Immunohistochemical Expression of p53 in Intestinal Epithelial Cells to Detect Dysplasia in Patients with Inflammatory Bowel Disease

Abstract

Introduction: Inflammatory Bowel Disease (IBD) has a genetic predisposition, in which patients are more prone to develop colorectal carcinoma. Dysplasia, a precursor of malignancy, can be very difficult to detect based on histopathological features alone. Tumour suppressor gene, p53, is overexpressed in IBD even when there is no histological evidence of dysplasia. Therefore, p53 can be used as a tissue biomarker for routine surveillance to initiate treatment for prevention of carcinoma. Aim: To identify the diagnostic utility of p53 immunohistochemistry in the detection of dysplasia in patients with IBD. Materials and Methods: This cross-sectional diagnostic study was conducted in the Department of Pathology at Pushpagiri Institute of Medical Sciences and Research Centre, Tiruvalla, Kerala, India, from June 2016 to June 2018. Total 31 cases of intestinal biopsies in patients with chronic bloody diarrhoea were selected for the study. Immunohistochemical (IHC) staining using anti p53 antibody was done in all the cases to detect the expressed protein. Statistical analysis was performed using Statistical Package for the Social Sciences (SPSS) version 20.0. Significance of p53 immunostains was done using Fischer’sexact test. Results: The age group of patients with IBD ranged from 15- 73 years with a bimodal age peak between 20-29 years and 60-69 years. Male predominance was seen among 20 cases while 11 cases were among females. Negative staining for p53 was seen in 28 cases which were negative for dysplasia histopathologically. Only one case which was histopathologically positive for dysplasia and one of the negative cases of dysplasia showed p53 positivity. Another case which was histopathologically positive for dysplasia showed negative staining for p53. Sensitivity of p53 in this study was 50% while the specificity was 96.55%. Conclusion: The finding of positive p53 expression in dysplasia positive case follows the fact that p53 mutations found in dysplastic mucosa precedes progression to neoplasia. In contrast, positive p53 expression in a case that was negative for dysplasia histopathologically, should be handled cautiously and warrants regular follow-up in order to prevent neoplastic progression. However, diagnosis of dysplasia should not be made in areas of active inflammation as inflammatory changes can lead to regenerative atypia which could result in over interpretation of histological features attributing it to dysplasia.

Keywords

• crohn’s disease
• colorectal cancer
• tumour suppressor gene
• ulcerative colitis