[Histopathology of oral "hairy" leukoplakia].

We studied biopsy specimens from ten male Caucasian patients with oral "hairy" leukoplakia. All patients either had the acquired immunodeficiency syndrome (AIDS) or showed symptoms of the AIDS related complex (ARC). On the basis of the specimens studied, we describe the histopathological features of this new entity and discuss the already established criteria. Histopathologically, "oral hairy leukoplakia" is characterized by a prominent confluent parakeratotic cornified layer, a subcorneal horizontal bandlike array of large ballooned epithelial cells with pale eosinophilic cytoplasm and a clear perunuclear halo. PAS staining revealed hyphae in two of the ten biopsies. The histopathological changes seen in oral "hairy" leukoplakia are characteristic, but not specific. Thus they must be differentiated from a variety of histologically similar looking dermatoses of the oral cavity.