Erythroplakic lesions in relation to oral lichen planus.

In a cohort of 740 referred patients with oral lichen planus eight patients were found with a sharply demarcated slightly depressed erythroplakic area. The histological examination of the biopsies from the erythroplakic lesion of the 8 patients showed seven with epithelial dysplasia. In addition, two of the lesions revealed a squamous cell carcinoma. In the erythroplakic lesion without dysplasia the histological picture was found to be characteristic of lichen planus. All eight patients were seen at later follow-up examinations (median observation period: 3.6 years) and in one patient a squamous cell carcinoma arose in the erythroplakic lesion during the control period. It is concluded that the reported erythroplakic lesions in relation to oral lichen planus seem to be premalignant and they should be followed and/or treated like oral erythroplakias.