Oral lichen planus (OLP) is a chronic mucocutaneous disease, which is considered a precancerous condition. OLP is a multifactorial disease with no conclusive treatment. Timely diagnosis and treatment of oral lesions are necessary steps to prevent malignant transformations and severe complications of oral cancer. This study aimed to evaluate the frequency and severity of malignant transformations in OLP.

In this study, 2400 files of patients who presented to the Oral Medicine Department of the Dental School of Semnan University of Medical Sciences from 2013 to 2018 were evaluated. Data were statistically analyzed using SPSS.

Forty patients (9 males and 31 females with the mean age of 45.2 years) were diagnosed with OLP (1.6%). The most common type of OLP was reticular (75%), and the least common was the ulcerative type. Since toluidine blue staining was positive for 4 patients (10%), a biopsy was done. The histopathological examinations showed one case with dysplasia (2.5%) and one case of carcinoma (2.5%).

According to the results, carcinoma and dysplasia can develop in OLP patients. Regular follow-ups are strongly recommended for timely diagnosis and treatment of malignant transformations.