Xeroderma pigmentosum: review and report of a case. Xeroderma pigmentosum is a rare inherited dermatosis that provides insight into the basic mechanism of carcinogenesis. It is a model disorder linking defective DNA repair with clinical abnormalities and neoplasia. UV light-induced damage to the skin begins early and results in multiple benign and malignant skin tumors, especially in sun-exposed areas of the head and neck. Oral cancers, primarily squamous cell carcinomas of the anterior third of the tongue, occur with greatly increased frequency. A patient with multiple facial neoplasia and oral manifestations of xeroderma pigmentosum is presented. The role of the dentist in surveillance of oral and perioral structures is emphasized. The dentist is advised against the use of UV light-curing units in these patients because UV-induced epithelial damage may cause dysplasia when DNA repair mechanisms are dysfunctional. 