[Detection of Epstein-Barr virus DNA in hairy leukoplakia by in situ hybridization]

Hairy leukoplakia (HL) is one of the commonest oral lesions associated with infection with the human immunodeficiency virus (HIV). This entity is regarded to be related to replicative Epstein-Barr virus (EBV) infection, in the epithelial cells of the oral mucosa. The present study was aimed at demonstrating the presence of EBV in 19 biopsy specimens, with clinical and histologic diagnosis of HL.

In situ hybridization technique was performed with a biotinylated probe employing formalin-fixed paraffin-embedded sections.

All cases exhibited a hybridization signal restricted to nuclei of keratinocytes that displayed a cytopathic effect in the routine microscopic study. The hybridization signal was confined to the nuclei of a large number of intermediate and superficial cell layers, and occasionally of the parakeratin surface.

It appears to exist a close relation between the presence of EBV and the development of HL. In situ hybridization technique with a biotinylated EBV DNA probes is a useful diagnostic tool, that allows a highly accurate diagnosis of HL, specially in those lesions with doubtful clinical and histopathological appearances. The HL represents the first known non-tumoral epithelial lesion associated to EBV infection.