The histopathologic evolution of recurrent herpes simplex labialis.

In a study of the natural history of recurrent herpes simplex labialis, we examined hematoxylin and eosin-stained sections of biopsies taken from lesions at various clinical stages. The earliest specific findings which could be recognized were changes within the epidermal cell nuclei, including peripheral clumping of chromatin, development of homogeneous "ground glass" appearance, and ballooning of nuclei. Eosinophilic intranuclear inclusion bodies were unusual and occurred in late lesions. Vacuolization was the earliest cytoplasmic alteration within keratinocytes. The herpes-induced changes began focally along the basal cell layer, but the entire epidermis was rapidly altered. Pilosebaceous units were commonly affected. Within the dermis, no cells with typical herpesvirus-induced changes were seen. In early lesions, mononuclear and polymorphonuclear inflammatory cells were equally prominent; in later lesions neutrophils were most numerous. Histopathologic changes of recurrent herpes simplex begin multicentrically within the epidermis and are present prior to the onset of physical findings.