Individual cells are enlarged to several times their normal diameter and display purplish intracytoplasmic and intranuclear inclusions with a somewhat crystalline shape. There is a variable amount of inflammatory infiltrate in the dermis. It is important to rule out the presence of a mixed viral infection, as it is not uncommon to see both HSV and CMV within the same section. Oral hairy leukoplakia is manifested by marked epithelial hyperplasia with a verrucous corrugated appearance. 35 Individual keratinocytes are altered dramatically, with ballooning degeneration giving rise to extensive pallor.
Minimal inflammation is seen in the lamina propria.
The differential diagnosis includes other ballooning degenerative lesions of the mouth, including chronic maceration and white sponge nevus. Electron microscopy as well as DNA in situ hybridization can be used to demonstrate viral particles in the epithelium, especially in the upper rather than lower portions. Zoster and OHL may occur in patients who are more immunocompetent. The differential diagnosis of herpesvirus infections clinically includes other chronic ulcerative conditions such as aphthous ulcerations, ulcerative opportunistic atypical mycobacterial and deep fungal infections, as well as traumatic ulcers. Verrucous lesions may mimic a number of different conditions, including epithelial neoplasms and infections associated with pseudocarcinomatous hyperplasia.