Malignant Transformation of Oral Lichen Planus and Lichenoid Lesions: A Retrospective Study on Iranian Population

Abstract

Background and Objectives: The present study aimed at assessing the malignant transformation rate (TR) of oral lichen planus (OLP) and lichenoid lesions (OLL) of patients at the School of Dentistry, Mashhad University of Medical Sciences. Methods: A retrospective cross-sectional study was conducted on 195 patients diagnosed with OLP or OLL at a single university dental center from April 2011 to March 2021. Eligibility criteria included all patients with a confirmed clinical and histopathological diagnosis of OLP or OLL during the specified period; patients with incomplete records or pre-existing dysplasia were excluded. Data on demographics, systemic disease history, medication use, lesion characteristics, and biopsy results were collected. Diagnosis was based on WHO guidelines for OLP and clinical and microscopic criteria for OLL. To ensure diagnostic consistency and mitigate bias, histopathological slides were re-evaluated by 3 independent oral pathologists, with inter-rater reliability assessed. Statistical analysis was performed using Chi-square or Fisher’s exact tests for categorical variables and the Mann-Whitney U test for continuous variables. The study evaluated the association between malignant transformation and variables such as lesion type, location, erosive nature, gender, and age. Results: Of the 195 patients (66.7% female, mean age 48.32 ± 13.92 years), 7 (3.6%) developed squamous cell carcinoma (SCC). This TR is notably higher than many rates reported in global literature, suggesting potential demographic or diagnostic variations. No significant association was found between malignant transformation and lesion type (OLP: 4.1%, OLL: 2%; P = 0.682), lesion location (P = 0.918), erosive nature (P = 0.468), gender [P > 0.99 or age (P = 0.453)]. Conclusions: The study highlights a 3.6% malignant TR in OLP and OLL, emphasizing the need for vigilant long-term monitoring. No specific risk factors were identified, indicating that all patients with these lesions should be considered at risk. The study’s limitations include its retrospective design, single-center setting, and the small number of transformation cases (n = 7), which restricts the statistical power to identify significant risk factors. Further large-scale, multi-center prospective studies are needed to explore potential risk factors and improve management strategies.