- Herpes Labialis is a manifestation of infection with Herpes Simplex Virus (HSV) on the oral mucosa and lips (See the HSV for virology and pathogenesis).
- Gross Appearance:
- Herpes Labialis appears as single or clusters of multiple vesicles 1-5mm in diameter containing clear fluid generally occurring around the lips and nostrils. Vesicles can eventually rupture, leaving shallow ulcers that heal within a couple weeks.
- Histological Appearance:
- Histopathology, herpes labialis begins as edema within and between infected epithelial cells. Keratinocytes eventually swell and undergo necrosis, resulting in further edema and generation of the grossly apparent vesicles. Characteristic to HSV, infected cells fuse together to form syncytiae of cells which are detectable on Tzank Smear.