Ultrastructural variations and assessment of malignant transformation risk in oral leukoplakia

Oral cancer is the most common malignancy in India, having a well defined precancerous state, leukoplakia. Various follow-up studies have shown that only 4 to 18% of oral leukoplakia lesions subsequently progress into invasive malignancy over a period of time. This study evaluates the potential of electron microscopy in the early detection of malignant changes in leukoplakia. The study revealed that of the 25 leukoplakia lesions examined, 7 showed changes akin to malignancy. Predominant ultrastructural alterations observed were reduplication and discontinuity of the basal lamina, basal cells with pleomorphic and bizarre nuclei containing perichromatin and interchromatin granules, prominent intercellular spaces and poorly formed desmosomes. Since none of these changes were evident under light microscopy the study demonstrates the value of electron microscopy in evaluating oral carcinogenesis. A long term follow-up of such patients is needed to understand the prognostic implications of these ultrastructural variation and how they can be used as a base line for better light microscopic evaluation.