[Oral hairy leukoplakia in AIDS. Histologic and ultrastructural study of 8 cases]

Oral hairy leukoplakia is a disease of the oral mucosa occurring almost exclusively in HIV-infected (mostly AIDS) patients and due to the opportunistic development of Epstein-Barr virus (EBV) within the oral epithelium. Clinically, it shows as whitish patches with a shaggy surface occurring on the lateral margins of the tongue, less frequently the buccal and labial mucosa or the soft palate. Histologically, it comprises parakeratotic hyperkeratosis, acanthosis and numerous koilocytoid cells within the stratum spinosum, i. e. cells with a pycnotic nucleus surrounded by a clear halo and pale-staining cytoplasm. Electronmicroscopy readily shows abundant Herpes-group viral particles within the upper epithelial layers. By immunohistochemistry, in situ molecular hybridization and Southern-blot EBV antigens and DNA have been demonstrated within the lesions whereas HPV and HIV are generally undetectable. In the present work we studied by light- and electronmicroscopy lesions from 8 HIV-seropositive individuals that fulfilled the clinical and histological criteria of OHL. Ultrastructural examination showed the presence in all cases of Herpes-type virions, which, in two of the cases studied by immunohistochemistry, proved to belong to the EBV. It is concluded that electronmicroscopy is a sufficiently sensitive examination to confirm the diagnosis of OHL suggested in the presence of an appropriate clinico-histological setting.