Malignant transformation of oral lichen planus

Aims: To investigate the malignant potential of oral lichen planus (OLP), a common mucocutaneous disease of unknown aetiology. The malignant potential of OLP is still controversial, with studies reporting malignant transformation rates of between 0 and 5.6%. We also aimed to identify factors that might be associated with malignant transformation. Methods: We retrospectively reviewed the records of 832 patients with histologically confirmed OLP treated at the Dental Hospital, Newcastle upon Tyne during the period 1983–1996. Results: Of these 832 patients, a total of seven (0.8%) developed intra-oral squamous cell carcinoma (SCC), including three cases of carcinoma in situ. It was noted that OLP patients with SCC are more likely to be women, relatively young and have a low tobacco and alcohol intake. However, they had a good long-term prognosis. Conclusions: We conclude that the risk of malignant transformation in OLP is real but not high. Clinicians should have a higher index of suspicion of the possibility of malignancy developing in OLP, because such patients are different from typical patients who develop oral malignancy. Follow-up for at least 6 years is recommended.