Oral leukoplakia, the ongoing discussion on definition and terminology.

I Van Der Waal

doi:10.4317/medoral.21007

Abstract

In the past decades several definitions of oral leukoplakia have been proposed, the last one, being authorized by the World Health Organization (WHO), dating from 2005. In the present treatise an adjustment of that definition and the 1978 WHO definition is suggested, being : “A predominantly white patch or plaque that cannot be characterized clinically or pathologically as any other disorder; oral leukoplakia carries an increased risk of cancer development either in or close to the area of the leukoplakia or elsewhere in the oral cavity or the head-and-neck region”. Furthermore, the use of strict diagnostic criteria is recommended for predominantly white lesions for which a causative factor has been identified, e.g. smokers’ lesion, frictional lesion and dental restoration associated lesion. A final diagnosis of such leukoplakic lesions can only be made in retrospect after successful elimination of the causative factor within a somewhat arbitrarily chosen period of 4-8 weeks. It seems questionable to exclude “frictional keratosis” and “alveolar ridge keratosis” from the category of leukoplakia as has been suggested in the literature. Finally, brief attention has been paid to some histopathological issues that may cause confusion in establishing a final diagnosis of leukoplakia. Key words:Oral leukoplakia, potentially malignant oral disorders, definition.

Highlights

Some pathologists will deny a diagnosis of leukoplakia in the absence of epithelial dysplasia, what is not in accordance with the recommendations from the “dental” literature. -5.2 Lichenoid dysplasia In 1985 the supposedly distinct entity of lichenoid dysplasia has been introduced in the literature [17]
It is well appreciated that a number of aspects of the presently discussed definition and terminology may not be valid in all parts of the world
The use of strict diagnostic criteria is recommended for predominantly white lesions or diseases for which a possible causative factor has been identified, e.g. smokers’ lesion, frictional lesion and dental restoration associated lesion

Summary

Introduction

The definition and terminology of oral leukoplakia and leukoplakialike (“leukoplakic”) lesions and disorders of the oral mucosa is the subject of discussion in the literature for many decades This discussion is mainly focused on clinical aspects, but is partly related to some histopathological aspects as well. In 2005, the definition of oral leukoplakia has been changed at a WHO supported meeting into: ‘A white plaque of questionable risk having excluded (other) known diseases or disorders that carry no increased risk for cancer’ [5]. During the latter meeting it has deliberately been decided to consider leukoplakia a potentially malignant- premalignant and precancerous are equivalent adjectives- disease and not a lesion since it is well known that cancer development not always occurs in or close to the leukoplakia but may occur at other sites in the oral cavity or the head-and-neck region

Dysplastic leukoplakia

Discussion and Conclusions