INTRODUCTION: This 10-year retrospective study analyzed the incidence of malignant transformation of oral lichen planus (OLP). The study also included dysplasia and oral lichenoid lesion (OLL) in the initial biopsy as a potential differential diagnosis.
MATERIAL AND METHODS: A total of 692 scalpel biopsies were taken from 542 patients (207 [38.2 %] men and 335 [61.8 %] women). Clinical and histopathological parameters were analyzed.
RESULTS: The parameters gender (p = 0.022) and smoking behavior (p < 0.001) were significantly associated with the severity of diagnosis. Mucosal lesions with an ulcerative appearance (p = 0.006) and those located on the floor of the mouth (p < 0.001) showed significantly higher degrees of dysplasia or were diagnosed as oral squamous cell carcinoma (OSCC). Smoking and joint disease appeared to be significant risk factors. Treatment with tretinoin in different concentrations (0.005-0.02 %) significantly improved diagnosis. Twelve patients (8 female, 4 male) showed malignant transformation to OSCC within an average period of 1.58 years. The malignant transformation rate (MTR) was higher for OLL (4.4 %) than OLP (1.2 %). If the first biopsy showed intraepithelial neoplasia, the risk of developing OSCC increased (by 3.5 % for squamous intraepithelial neoplasia (SIN) II and by 6.7 % for SIN III).
CONCLUSION: Although we cannot rule out that OLP is a premalignant oral condition, we can confirm that OLP had the lowest MTR of all diagnoses.