[Verrucous carcinoma of the tongue occurring on lesions of lichen planus].

BACKGROUND: Verrucous carcinoma of the oral cavity is a rare entity that was formerly controversial. Etiopathogenesis remains unclear, notably as for its possible association with lichen planus. We report a case of verrucous carcinoma occurring in lesions of lichen planus of the tongue. CASE REPORT: A 78-year old, non smoking patient, with past history of cutaneous lichen planus presented for lesions of oral lichen planus affecting both the tongue and the palate. A treatment by topical tretinoin improved him in a spectacular way and brought about a remission which lasted 5 years. A recurrence occurred when the treatment was stopped; new whitish, warty cauliflower-like lesions appeared on the tongue. A biopsy confirmed the clinical suspicion of verrucous carcinoma. A laser resection was performed. Three months later, another recurrence was observed. A chemotherapy associating isotretinoin and methotrexate eliminated all lesions. The patient's condition is considered stable, under treatment, one year later. DISCUSSION: Verrucous carcinoma is a rare slow-growing oral tumor that is chiefly exophytic and does not metastasize, but it can invade and destroy oral tissues. Its clinical presentation contrasts with benign histologic features: papillomatosis, acanthosis, dysplasia in variable degrees. The occurrence on lesions of lichen planus, although "classic", is very rarely found in the literature. The treatment is not well codified. An additional chemotherapy seems necessary to prevent recurrences.