Proliferative verrucous leukoplakia: unusual locations of oral squamous cell carcinomas, and field cancerization as shown by the appearance of multiple OSCCs.

Proliferative verrucous leukoplakia (PVL) is an uncommon entity with a high tendency to develop oral squamous cell carcinomas (OSCCs). The objective of this study was to analyse the presence of various OSCCs in the same patient with PVL. We studied 19 patients with PVL who had developed at least one OSCC. We analysed how many of these developed more than one OSCC over a period between 24 and a maximum of 130 months, indicating the location of their OSCC, clinical type and the time lapse between the appearance of each of the different OSCCs in the same patient. Of the 19 patients, 10 presented more than one of these cancers, one of whom even went on to develop five different cancers. The most frequent location of OSCC was the gingiva and the palate; the least common was the tongue/floor of mouth. Ninety percent were women and 20% were smokers. The average time elapsed between the detection of the first tumour and the appearance of the second was 19.20 months (SD 13.41). Our patients with PVL developed a high frequency of OSCCs, on many occasions manifesting several cancers at different oral locations, thus demonstrating the field cancerization of this entity. The OSCC in PVL patients were at sites quite uncommonly affected in patients who develop OSCC in the absence of PVL.