[Oral lichen planus and cancer. Apropos of 2 cases].

Malignant changes in oral lichen planus lesions are still the subject of controversy. Two new cases provide supportive data for this thesis. Case 1: A 64 year old non smoking diabetic woman presented with combined atrophic lichen planus and erythroplasia lesions of the right buccal mucosa and a unique reticular lichen planus lesion of the left buccal mucosa. Both lesions were histologically confirmed. Despite treatment, degeneration of the Bowen's type lesion into an epidermoid carcinoma was noted within 11 months. Case 2: A 47 year old non smoking woman consulted for combined cutaneous and oral lichen planus lesions. Clinical examination showed an "acute" oral lichen planus associated with extensive ulcerative, atrophic and reticular lesions involving almost the total oral mucosa. Histology of a left buccal biopsy confirmed the diagnosis. Systemic and local corticotherapy produced marked improvement in her condition and she was not seen for five years. Follow up examination then detected a proliferative ulcerative type of epidermoid carcinoma on the left buccal mucosa. These findings appear to fulfil the clinical and histologic criteria suggestive of development of epidermoid carcinoma on a lichen planus lesion.