Oral lichen planus shows higher expressions of tumor suppressor gene products of p53 and p21 compared to oral mucositis. An immunohistochemical study.

OBJECTIVE: Oral lichen planus (OLP) has been speculated to be a chronic inflammatory disease with potential for malignant progression. The aim of this study was to establish a hypothesis on the difference between OLP and oral mucositis (OM) in terms of tumor suppressor gene expression.

DESIGN: Computer based image analysis of immunohistochemical expressions of p53 and p21 was investigated in 18 samples of OLP, 10 normal oral epithelium (NOE), 10 oral squamous cell carcinoma (OSCC), 13 OM, 20 oral focal keratosis (OFK), and 30 samples of oral epithelial dysplasia (OED). Representative fields were digitized and analyzed.

RESULTS: Using independent samples Student's t-test, p53 and p21 the mean percentages of positive nuclei (MPPN) of p53 (40.27%) and of p21 (39.98%) in OLP were significantly higher than that of NOE, OFK and OM (15.06%, 27.87%, 30.08% and 16%, 31.09%, 33.92% respectively, p<0.001). MPPN of p53 in OLP was not different from that of mild OED (40.5%, p=0.85) but lower than of moderate and severe OED, and OSCC (49.78%, 61.36%, 78.16% respectively; p<0.001). MPPN of p21 in OLP was lower than that of moderate and severe OED, and OSCC (47.72%, 57.9%, 85.44% respectively; p<0.001) but slightly higher than that of mild OED (39.86% p=0.81).

CONCLUSIONS: As the expression of p53 and p21 in OLP was significantly higher than that of oral mucositis with no significant difference from mild epithelial dysplasia, OLP might need to be followed up and monitored more closely to detect early features of transformation, if any, compared to non-specific oral mucositis which needs no close follow-up.