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.