Risk of malignant transformation in oral lichen planus and oral lichen planus with dysplasia: A retrospective clinical study of 435 histologically verified cases

BACKGROUND: Chronic activity of the subepithelial lymphocytic infiltrate may induce epithelial changes associated with malignant transformation (MT) in oral lichen planus (OLP) cases. OBJECTIVES: This study compared the risk of developing oral squamous cell carcinoma (OSCC) in a large cohort of patients with OLP and OLP with epithelial dysplasia (OLD). Special attention was paid to carcinoma location and clinical factors, such as desquamative gingivitis and reticular, erosive or ulcerative status. MATERIAL AND METHODS: This retrospective study included 435 histologically verified OLP/OLD cases treated between 2004 and 2024. To assess risk factors, medical history data on medication, smoking and comorbidities was collected. Clinical and pathological aspects were correlated. Statistical analyses were performed using SigmaXL software. RESULTS: Of the cases included in the study, 59.8% were classified as OLP (260/435) and 40.2% as OLD (175/435). A case was considered a true MT only if it followed the OLP/OLD biopsy results. According to this criterion, 30 OSCCs were diagnosed in 21 patients. Oral squamous cell carcinoma developed in 2.3% of OLP cases (6/260) and 8.6% of OLD cases (15/175), with a statistically significant difference between the groups (p = 0.0027). The most common site for OSCC was the gingiva/alveolar mucosa, accounting for 33.3% (10/30) of tumors, followed by the tongue (20.0%, 6/30). Two alveolar carcinomas were located at sites of peri-implantitis associated with desquamative gingivitis. In 2 patients, synchronous OSCCs were diagnosed in the maxilla and mandible. CONCLUSIONS: In this study, 8.6% of patients with OLD developed OSCC. Although OLP without dysplasia still carries a risk of OSCC, this risk was approx. 4 times lower, at 2.3%. Cases with desquamative gingivitis require close monitoring due to their higher risk of carcinoma development. We recommend careful observation of desquamative gingivitis around dental implants or in areas of ongoing dental inflammation. Surgical revision with biopsy should be considered if a resorptive process around an implant is suspected.