Oral lichen planus and squamous carcinoma. Case report and update of the literature.

A case of squamous cell carcinoma of the tongue arose in the plaque form of oral lichen planus. The literature on lichen planus is reviewed with emphasis on the issue of malignant transformation. Squamous carcinoma develops in 0.3% to 3% of patients with oral lichen planus (range, 0% to 10%). The average age of individuals with this complication is 50 to 55 years; 50% to 60% are men. Forty-four percent to 60% of patients have the erosive form of the disease, 28% to 34% plaque type, and 16% to 28% reticular. The mean interval from onset of the oral lesions to the development of cancer is nine to 12 years (range, three months to 40 years). Forty-six percent to 54% of the cancers occur on the buccal mucosa, 30% on the tongue, 16% on the lower lip, and 8% in miscellaneous sites. Twenty-four percent to 50% of the individuals also have cutaneous lichen planus.