Malignant transformation of oral leukoplakia: a multicentric retrospective study in Brazilian population

Abstract

Background: Among the oral potentially malignant disorders, leukoplakia stands out as the most prevalent. The purpose of this study was to analyse the clinical-pathological features of oral leukoplakia in groups of patients from three major pathology centers in two different regions of Brazil, in order to determine which factors would be associated to the clinical risk of malignant transformation.

Material and methods: A total of 148 patients was analyzed, and data regarding gender, age, site, classification of the clinical subtype, harmful habits such as use of tobacco and alcohol, time of evolution and presence of dysplasia were collected. The association between risk factors and malignant transformation was investigated using the chi-square test and Fischer's exact test for correlation of variables. A significance level of 5% (p≤0.05) was used.

Results: The mean age of the patients was 60 years, and 56% were female. Most of the lesions (34,5%) were located in the lateral and ventral regions of the tongue. Of the 148 patients, ninety had clinical follow-up. Malignant transformation occurred in 13 patients (8.8%), with an average of 44 months of follow up.

Conclusions: Non-smoker, nonhomogeneous clinical presentation, location at the tongue, and the presence of high degree of dysplasia were statistically relevant factors associated with a higher risk of transformation transformation.

Figure 1

Different clinical presentations of oral leukoplakia. a) A 63-year old male patient, non-smoker, presenting a single lesion on the hard palate, clinically diagnosed as homogeneous leukoplakia. Further microscopic analysis classified the specimen as being of low risk. b) A flat, homogeneous leukoplakia involving the right inferior gingiva of a 78-year old , non smoker female, whose lesion was microscopically considered of low risk. c) A 71 year-old female former smoker exhibiting an extensive lesion with variation of color, on the left border of the tongue, classified as nonhomogeneous leukoplakia. The case was classified as having high risk after microscopic assessment. d) An 82year-old female and non smoker patient, presenting a reddish and white lesion on the palate, which did not show any dysplasia on the microscopic analysis, being classified as low risk.

Figure 2

Cases of proliferative verrucous leukoplakia. a) White and reddish lesions of nodular and flat aspects involving the left and right sides of the palate, respectively. The patient is a 75-year old male smoker. The more dense lesion was microscopically classified as high risk. b) A 74-year old male and tobacco user presenting a large lesion, which covered both sides of the hard palate. c) A 31-year old non-smoker female patient, whose prior diagnosis was LVP, was diagnosed with squamous cell carcinoma in the left tongue border after a 71-month follow-up period. d) Another case which progressed to OSCC. A 55-year old male, non-smoker, was initially diagnosed with nonhomogeneous leukoplakia. The malignant transformation occurred after 19 months of follow-up.

Figure 3

Comparison used the Fisher’s test for the establishment of relations between the malignancy and lesions homogeneous x non homogeneous (a) high risk dysplasia x low risk (b) smokers x non-smokers (c) and location (d).