Oral leukoplakia is considered the most common potentially malignant disorder of the oral cavity. Therefore, its early diagnosis is essential before a carcinoma occurs. 

Dídac Sotorra Figuerola. Full member of the Spanish Society of Oral Surgery (SECIB). Professor of Oral Medicine, TMJ and Orofacial Pain Unit of the Master’s in Oral Surgery and Orofacial Implant Dentistry at the University of Barcelona.  

The most widely accepted definition of oral leukoplakia (OL), described by the World Health Organization (WHO), refers to any lesion or predominantly white plaque of a questionable nature, having clinically and histopathologically excluded any other definable white disorder or disease ^(1,2). 

Despite being the most frequently occurring, potentially malignant oral disorder, its estimated prevalence is under 1% in the general population. Conventional OL affects mostly men. The age period in which it mainly occurs is the fifth decade of life in men and the seventh decade in women, and it rarely occurs during the first two decades of life⁽³⁾. 

It is usually closely related to smoking, although it may also appear in non-smokers, in which case it is considered idiopathic. OL has classically been divided according to its clinical characteristics: homogeneous and non-homogeneous. The latter are then subdivided into nodular and exophytic erythroleucoplakias⁽⁴⁾.

Initially, the provisional diagnosis is clinical following a complete case history study and a thorough oral examination. In order to come to a definite diagnosis, it is essential to perform a biopsy and a histopathological study. 

The rate of malignant transformation from leukoplakia into cancer varies considerably, but it has been established that the annual risk of malignancy is between 2% and 3%⁽⁴⁾. 

There is a particular form of oral leukoplakia known as Proliferative Verrucous Leukoplakia (PVL) or Proliferative Multifocal Leukoplakia (PML). It was first described in 1985 by Hansen et al.⁽⁵⁾ and is a particularly aggressive form of leukoplakia. It is usually related to non-smoking women in around the sixth decade of life. It is characterised by the appearance of multiple white plaques that grow and spread throughout the oral mucosa, predominantly affecting the gums and the buccal mucosa^(6,7). The most striking clinical features are its multifocality, the long period of evolution and the high rate of malignancy of over 50%⁽⁸). 

Regarding OL and PML treatment, different therapeutic alternatives have been suggested: conventional surgical removal, CO2 laser surgery and retinoid treatment, amongst others^(4,6,9). For now, none of these treatments has sufficient scientific support, and they have not been proven effective in preventing the recurrence and malignancy of leukoplakia. Our recommendation is to get regular check-ups to detect a change in behaviour as early as possible and thereafter to have a biopsy taken for early diagnosis. 

CLINICAL CASE 

The subject is a 46-year-old woman who was referred to the Master’s in Oral Surgery and Orofacial Implant Dentistry at the University of Barcelona with several asymptomatic white lesions in the oral mucosa. 

The subject had no medical history of interest nor reported any toxic habits (she did not smoke or drink). 

In the intraoral clinical examination, several homogeneous and non-homogenous, well-defined and irregular white plaques were observed (Figures 1-4). None of the white lesions came away by scraping nor were they hard to the touch. 

The provisional clinical diagnosis was proliferative verrucous leukoplakia/proliferative multifocal leukoplakia and several incisional biopsies were performed to obtain a histopathological analysis. Epithelial hyperplasia with hyperkeratosis and low-grade (mild) epithelial dysplasia was observed on the floor of the mouth (Figure 5). 

With all of this information, the definitive diagnosis was proliferative verrucous/multifocal leukoplakia. Due to the high risk of malignancy of the lesions, it was decided to carry out a strict follow-up of the patient with periodic reviews every 3-6 months, and the patient was instructed in oral self-exploration for early detection of any further developments or changes in the process. 

CONCLUSIONS 

Early diagnosis of OL is essential before a carcinoma occurs. Oral cancer is a common malignant neoplasia, ranking up to sixth in terms of frequency among cancers. In addition, it still shows high morbidity and high mortality, with a survival rate after five years of under 50%. These are alarming figures considering how easy it is to access the oral cavity for clinical examination, which would allow for early diagnosis. The importance of the dentist and the dental hygienist in primary prevention and the early diagnosis of potentially malignant oral disorders and oral cancer cannot be overstated, since these are the health professionals who have greatest access to the oral cavity. In addition, it must be pointed out that biopsy and histopathological study of any oral lesion that is suspicious or that does not heal in 15 days is essential.