Two cases of oral leukoplakia possibly associated with human papillomavirus

: Two cases of oral leukoplakia were studied immunohistologically and ultrastructurally. By means of avidin-biotin peroxidase complex technique using papillomavirus specific antibody, distinct nuclear staining of epithelial cells of middle and upper layers was observed in both cases. Further evidence for the presence of human papillomavirus was obtained by the electron micrograph, which revealed virus-like particles (30-40 nm in diameter) within the nucleus.