Oral hairy leukoplakia: a histopathologic study of 32 cases

Oral hairy leukoplakia (HL) was studied in 32 patients infected with the human immunodeficiency virus (HIV). Features most often found were parakeratosis of variable thickness, acanthosis, little or absent submucosal chronic inflammatory cell infiltrate, association with candidiasis in 71.8%, and intranuclear herpetic type inclusions in keratinocytes, associated with ballooned or ground-glass cytoplasm. The last feature was found in all biopsies and was most striking at the top of the stratum spinosum, just beneath the parakeratotic surface. We consider that intranuclear inclusions are the histologic hallmark of HL, which, together with other features described, make it possible to diagnose HL specifically by light microscopic examination. Ultrastructural studies were carried out in 20 cases. Viral particles of the human herpesvirus group were detected in 17 cases. Particles of papillomavirus (HPV) were not found in any of the specimens. Immunohistochemical studies were made in 26 cases using a rabbit antiserum to papillomavirus. Nuclear positivity was observed in 25 cases. Despite such apparently contradictory results, we think that a cross reaction may exist between the antiserum used against HPV and some antigens of the Epstein-Barr virus (EBV).