What is Leukoplakia?
Leukoplakia is a predominantly white patch or plaque of the oral mucosa that cannot be wiped away and cannot be clinically or histologically characterized as any other definable disorder. 1
Definition and Clinical Characteristics
- Leukoplakia is defined as a white patch or plaque on the oral mucosa that cannot be removed by scraping and is not explained by the presence of any other disease 1, 2
- The key distinguishing feature from oral candidiasis is that leukoplakia cannot be scraped off, whereas candidal plaques can be easily removed with a tongue depressor 3
- Leukoplakia carries an increased risk of cancer development either within the lesion itself, in adjacent areas, or elsewhere in the oral cavity or head-and-neck region 4
Classification and Risk Stratification
Leukoplakia is classified into two main types based on appearance and malignant potential:
- Non-homogeneous leukoplakia has a significantly higher risk of malignant transformation compared to the homogeneous type 5, 6
- Homogeneous leukoplakia presents as uniform white patches with lower transformation risk 5
Histopathologic Features
The microscopic characteristics include:
- Hyperkeratosis (either orthokeratotic or parakeratotic type) and acanthosis of the epithelium 2
- Various degrees of chronic inflammatory infiltrates in the lamina propria 2
- Epithelial dysplasia may be present with features including loss of basal cell polarity, increased nuclear-cytoplasmic ratio, irregular epithelial stratification, abnormal mitotic figures, and cellular pleomorphism 2
Malignant Potential
- Leukoplakia is classified as a potentially malignant disorder rather than a "precancerous lesion," reflecting that not all lesions will transform to cancer 7
- Up to 85% of all precancerous oral lesions manifest as leukoplakia 2
- The overall malignant transformation rate does not exceed 4%, though some studies report up to 16% transformation in lesions with dysplasia 2
- Leukoplakia is the most common oral mucosal lesion, evident in approximately 3% of adults 2
Diagnostic Approach
- Diagnosis requires excluding other definable white lesions through clinical and histopathologic examination 1
- For lesions with an identified causative factor (smoking, friction, dental restoration), a final diagnosis can only be made retrospectively after successful elimination of the causative factor within 4-8 weeks 4
- Biopsy with histopathologic examination is essential to assess for dysplasia and rule out other conditions 1