By Dr. Vishaal Bhat on Tuesday 6 November 2007 with 0 comments

Leukoplakia is, according to the WHO (World Health Organization), literally a clinical term describing a

“white, non-effaceable region of a mucous membrane that cannot be associated with any defined disease”.

Different usages and interpretation of the term leukoplakia caused many misunderstandings mainly because the term has been used at clinical and patho-morphological literature most definitely for precancerous lesions.

In clinical praxis, one has to consider that differentiation among a benign symptomatic mucous diseased patch (a white patch), a precancer, and a carcinoma in situ can be made only according to the cytological and patho-histological criteria. At present, classification of leukoplakias according to the degree of dysplasia is preferred which means studying mainly polymorphism of cells and cell nuclei, number and irregularities of mitoses, disappearance or damage of a regular arrangement of mucous layers and continuity (sharpness) of the basal membrane, by means of bioptic sampling.

Classification of precancers (and all pre-neoplasias in general) in pathology has a non-disputable importance for a prognosis of the disease. For leukoplakias, a crucial criterion for determination of degree of malignity is the absence or presence of a dysplasia. Leukoplakias without signs of a dysplasia have a benign character and classify in the group of precancers at the widest sense (a facultative precancer).

A leukoplakia with an apparent dysplasia of the moderate or high degree is already a precancer in the narrowest sense (an obligatory precancer) or even an early stage of a carcinoma (a carcinoma in situ). This brief and simplified description of pathological classification of leukoplakias can be concluded with a fact that the higher the degree of dysplasia, the higher the frequency of transformation of a leukoplakia into a mucous carcinoma.

Two more notes are worth mentioning from the clinical point of view:

  1. The first note provides a closer look on quantitative relationships of individual types of leukoplakia, classified according to the degree of dysplasia. Among all types of leukoplakia, forms with no signs of dysplasia or with very low degree of dysplasia represent 74%, forms with moderate dysplasia 17%, and with high degree of dysplasia 6%. Remaining 3% can already be classified as carcinomas in situ (Seifert and Burghardt).
  2. The second note concerns over-growth of Candida albicans at the site of a leukoplakia related infection and its vicinity. Such an infection always presents a risk factor and signals weakening of the cellular immune system. A thrush is observed at as much as 35% cases of leukoplakias with high degree of dysplasia.

The oral cavity leukoplakia occurs most frequently during the fifth decennium and its occurrence rate increases with age. Men suffer from it more often than women. Not only age, but also a location are important for prognosis. Leukoplakias on the palate and alveolar mucosa have a minimum tendency to malignant transformation and they almost never recur. On the other hand, leukoplakias of the mouth base possess the least optimistic prognosis due to their tendency to a malignant growth.

From clinical and macroscopical perspectives, these diseases include leukoplakia plana, verrucosa and errosiva.

Microscopic pictures correspond to this division, identifying the flat form (plana), papillary-endophytic form, and papillomatous-exophytic form.

  • The flat form of leukoplakia presents about 70% of all cases and appears most often on the mucosa of lips, cheeks and tongue.
  • The papillary-endophytic form of leukoplakia presents about 22% and it is mostly diagnosed on the mouth base and the alveolar ridge.
  • The papillomatous-exophytic form is the least common form (3% of incidence) and appears mostly at the palate and the alveolar ridge.
  • While the simple flat form of leukoplakia rarely turns into a precancer.
The verrucous form (grooved patch with wartlike projections) and especially the erosive form (de-epithelized ulcerous patch) possess clearly higher trend towards a malignant transformation into a carcinoma (up to 38% in case of erosive forms, Seifert). These two forms should always rise a clinician’s doubt about a precancer of an obligatory type or even an initial form of a carcinoma.

This leads to an important observation that every clinician, including those from the field, get involved in the process of an early diagnostics and therapy just upon a slightest suspicion of a malignant tendency.

A clinician has to make sure that these services are delivered. In practice it means that a suspicious lesion is subjected to analysis by a specialist which is in patient’s own interest.

A specialist determines the degree of a leukoplakia lesion by the diagnostic excision and organizes further therapy based on its results. The issue of precancers is predominant especially in the stomatologic field since malignant processes at the oro-facial area can be recognized at early stages. This puts a great deal of oncological responsibility onto all stomatologists.

Awareness of this responsibility should result at a close and active collaboration of a local clinic with a specialized department capable of dealing with problems of stomatological oncology.

Category: Stomatology Notes



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