An immunohistochemical evaluation of podoplanin expression in oral leukoplakia and oral squamous cell carcinoma to explore its potential to be used as a predictor for malignant transformation

BACKGROUND: Oral leukoplakia (OL) is a potentially malignant disorder with increased risk for the development of oral squamous cell carcinoma (OSCC). Many cases of OSCC arise from the malignant transformation of preexisting OL. However, the risk of progression into OSCC and the possible prediction of malignant potential of OL remain inconclusive. Recent studies have shown that podoplanin, a mucin-like transmembrane glycoprotein specifically expressed in lymphatic endothelial cells, is expressed in various neoplasms including OSCC, indicating its possible biologic role in tumor cells. In this study, an evaluation of podoplanin expression in OL and OSCC has been carried out to assess its potential role as a biomarker to predict the possibility of malignant transformation in OL cases. AIMS AND OBJECTIVES: To assess the usefulness of podoplanin as a potential biomarker for predicting the risk of malignant transformation in OL, by comparing its immunohistochemical expression in OL and OSCC. MATERIALS AND METHODS: Archival paraffin-embedded blocks of 25 OL cases with varying grades of dysplasia and 30 OSCC cases showing its varying grades were selected. Sections were subjected to immunohistochemical staining for podoplanin and compared with the control group for evaluation of results in the three groups. RESULTS: A statistically significant increase in podoplanin expression was observed from normal mucosa through OL to OSCC. In the OL cases, the podoplanin staining score progressively increased from mild dysplasia to carcinoma in situ, whereas in OSCC, well-differentiated group showed the maximum expression of podoplanin. CONCLUSION: The progressive increase in podoplanin expression through the increasing grades of dysplasia in OL is suggestive of an increased risk for malignant transformation with increased expression of podoplanin in OL cases. A high podoplanin expression in the well-differentiated OSCC may indicate a vital role for podoplanin in the early stages of tumorigenesis.