Malignant transformation of oral proliferative verrucous leukoplakia: a series of 48 patients with suggestions for management

Abstract

Proliferative verrucous leukoplakia (PVL) is a rare and refractory form of oral mucosal leukoplakia of unknown origin, characterized by high rates of malignant transformation. Different diagnostic criteria, terminologies, and therapeutic approaches have been proposed since the first report in 1985. There remains no general agreement regarding the clinical and histological diagnosis, prevention, and correct management of this disease. This retrospective study investigated 48 patients affected by PVL showing at least one malignant transformation and followed up at 2-month intervals. Twenty-five were female (52.1%) and 23 (47.9%) were male; their median age was 67 years (range 40-93 years). Follow-up ranged from 18 to 240 months. Clinical examination included the use of Lugol's solution to prevent clinical underestimation of the margins and toluidine blue for suspicious areas. Surgical excision by scalpel was the preferred treatment for suspicious lesions, with only five carcinomas surgically removed by diode laser and two by CO₂ laser. All specimens were accurately mapped after formalin fixation. Fifteen patients (31.3%; 10 female, five male) developed one oral carcinoma, while 33 (68.7%) developed two or more primary tumours (range 3-12). Only four patients (8.3%), who developed between 2 and 8 oral squamous cell carcinomas (OSCCs), died of tumour-related causes. The pre-surgical clinical workup, subsequent surgical treatment, and follow-up are key to success for patients affected by PVL with malignant transformation into stage 1 OSCC and/or verrucous carcinoma, leading to a high overall survival rate.

Keywords: malignant transformation; oral cavity; oral squamous cell carcinoma; potentially malignant disorders; proliferative verrucous leukoplakia.