Viral Blisters

These fluid -filled cavities that develop in the superficial layers of skin or mucous membranes form tense, circumscribed elevations on a hyperemic base that wither, dry, and crust over after a few days or rupture to form shallow ulcers. With the exception of smallpox, healing rarely leaves permanent scars. The many causes of viral blisters- varicella, herpes zoster, herpes simplex, herpangina, hand, foot, and mouth disease, echovirus exanthems, vesicular stomatitis, variola, vaccina, cowpox, monkeypox, milker's nodule, and orf- are discussed.