A 6-year-old boy presents with painful sores on his upper lip. He was seen for a flu 1 week ago. The lesion appears as 0.2- to 0.4-cm vesicles with focal ulceration. Which of the following is the most likely histologic feature of this skin lesion?

Herpes labialis (cold sores, fever blisters) and herpetic stomatitis are caused by herpes virus type 1. They are among the most common viral infections of the lips and oral mucosa in both children and young adults. The disease starts with painful inflammation of the affected mucosa, followed shortly by the formation of vesicles. These vesicles rupture and form shallow, painful ulcers. Microscopically, the herpetic vesicle forms as a result of "ballooning degeneration" of the epithelial cells. Some epithelial cells show intranuclear inclusion bodies. At the edge of the ulcer are large, multinucleated, epithelial cells with "ground glass" homogenized nuclei, often exhibiting nuclear molding. The ulcers heal spontaneously without scar formation. Acute arteritis (choice A) does not cause the described lesions. Choices B, C, and E do not represent acute vesicular lesions.Diagnosis: Herpes labialis