BACKGROUND: Proliferative verrucous leukoplakia (PVL) is a rare variant of oral leukoplakia (OL) with a high tendency for malignant transformation. PVL starts as a flat hyperkeratosis. During the course of the disease verrucous lesions develop. AIM OF THE STUDY, MATERIAL AND METHODS: Due to the scarcity of reports on PVL five cases of PVL are presented. Clinical and histopathological findings in five female patients with PVL were evaluated retrospectively. RESULTS: The clinical appearance of PVL was characteristic as compared to criteria described in the literature. The average period of observation in these cases was short (1.7 years). There were 3.6 different localizations observed per patient. The buccal mucosa, gingiva, and edentulous alveolar ridge were most often affected. One patient had already developed squamous cell carcinoma prior to referral. The others developed malignancies during follow-up. Recurrences and secondary malignancies could not be avoided using different therapeutic modalities. Two patients died from PVL. The characteristic spectrum of histopathological findings in PVL was observed. Homogeneous flat leukoplakias are characterized by acanthosis, hyperkeratosis, and often parakeratosis. Epithelial dysplasia is not seen. The proliferative verrucous stage of the disease is characterized by papillomatous epithelial growths with signs of slight epithelial dysplasia and subepithelial infiltration with immunocompetent cells. Stages of transformation may result in verrucous carcinoma or squamous cell carcinoma. CONCLUSIONS: PVL is associated with a very high rate of malignant transformations. These, as well as recurrences, cannot be avoided with present-day therapies. In order to define the biological profile of PVL more clearly, multicenter studies are necessary to reveal possible etiologic factors and concepts for therapy.
