ABSTRACT
A study of oral lesions in five patients with erythema multiform was carried out to reveal the histopathological and ultrastructural features of this disease in a trial to shed more light on possible diagnostic criteria that may be helpful in the histological diagnosis of this disease, especially if it is limited to the oral cavity, or if it is not accompanied by the characteristic target lesions. The oral lesions were associated with the classical appearance of the skin lesions in three patients, while in the other two cases they were not the only manifestations of the disease. Biopsies of the cheek mucosa were processed for light and electron microscopic examinations. No difference was noticed in the histopathological features of the disease between patients with or without skin involvement. Alterations were observed in whole epithelial layers, basal lamina and the underlying connective tissue