Detection of EBV and HPV DNA sequences in oral "hairy" leukoplakia by in situ hybridization

Oral "hairy" leukoplakia (OHL) is a white lesion of the oral mucosa, usually located on the lateral tongue among human immunodeficiency virus (HIV) positive acquired immunodeficiency syndrome (AIDS)-risk patients. The lesion has been reported to be associated with Epstein-Barr virus (EBV) and human papillomavirus (HPV). Twenty surgical biopsy specimens were evaluated for the presence of HPV genus-specific antigen, HPV 2/4, 6/11, and 16/18 DNA and EBV DNA by in situ hybridization employing formalin-fixed paraffin-embedded sections. Three cases exhibited immunoreactivity for HPV genus-specific antigen, with localization in cytopathically altered upper spinous layer keratinocytes. HPV 16, 18, or related DNA sequences were identifiable in a single case. Alternatively, employing an EBV long internal repeat subgenomic probe, 19 cases were found to harbor EBV DNA. In all positive cases, the hybrids were localized to upper spinous layer keratinocytes exhibiting nuclear/cytoplasmic vesiculation. It is concluded that OHL is consistently associated with EBV; furthermore, viral replication, as evidenced by DNA localization, corresponds to ultrastructural evidence of capsid and envelope assembly in the more differentiated layers of oral epithelium.