Dermatology, Venereology and Leprosy
Viral Infections of the Skin
Cutaneous viral infections for MBBS and NEET-PG: herpes simplex and zoster, Tzanck smear, Hutchinson's sign, warts and molluscum, and antiviral therapy, mapped to NMC codes DR8.
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Viral Infections of the Skin
Cutaneous viral infections for MBBS and NEET-PG: herpes simplex and zoster, Tzanck smear, Hutchinson's sign, warts and molluscum, and antiviral therapy, mapped to NMC codes DR8.
Cutaneous viral infections range from the recurrent cold sore to sexually transmitted warts. This chapter covers herpes simplex and zoster with the Tzanck smear and Hutchinson's sign, chickenpox, human papillomavirus warts and molluscum contagiosum, and the antiviral and destructive treatments that apply to each.
High-yield: Viral Infections of the Skin
- Herpes simplex virus type 1 typically causes orolabial herpes, and type 2 causes genital herpes, though there is overlap.
- Herpes labialis, or cold sores, presents as grouped painful vesicles on an erythematous base, often recurring at the same site after a prodrome of tingling.
- The virus remains latent in sensory ganglia and reactivates with fever, sunlight, stress or immunosuppression.
- A Tzanck smear from the base of a fresh vesicle shows multinucleated giant cells in herpes and varicella infections.
- Chickenpox (varicella) shows crops of lesions in different stages at once, giving a dew-drop-on-a-rose-petal appearance.
- Herpes zoster (shingles) is reactivation of latent varicella-zoster virus in a single dermatome, with painful vesicles that respect the midline.
- Ophthalmic zoster with vesicles on the tip of the nose, Hutchinson's sign, warns of eye involvement through the nasociliary nerve.
- Post-herpetic neuralgia is a common and troublesome complication of shingles, more so in the elderly.
- Viral warts are caused by human papillomavirus, and the plantar wart interrupts skin lines and is painful on lateral compression.
- Molluscum contagiosum is a poxvirus infection giving discrete dome-shaped umbilicated papules, common in children and in HIV disease when it can be extensive.
- Widespread or giant molluscum in an adult should prompt testing for HIV infection.
- Genital warts (condylomata acuminata) are sexually transmitted, and certain high-risk HPV types are linked to cervical and anogenital cancer.
- Oral aciclovir, valaciclovir or famciclovir shorten and reduce the severity of herpes simplex and zoster when started early.
- Warts and molluscum are often self-limiting but can be treated with cryotherapy, topical agents or curettage.
Cutaneous viral infections
- **Herpes simplex:** Grouped vesicles, recurrent, latent in ganglia. Tzanck giant cells, aciclovir.
- **Herpes zoster:** Dermatomal painful vesicles, Hutchinson's sign, post-herpetic neuralgia.
- **Viral warts:** Human papillomavirus; plantar warts painful, genital warts sexually transmitted.
- **Molluscum contagiosum:** Umbilicated papules; extensive form suggests HIV in adults.
NMC competencies in this chapter
- **DR8.1:** Aetiology, microbiology, pathogenesis and clinical features of cutaneous viral infections
- **DR8.2:** Distinguishing herpes simplex and herpes labialis from other lesions
- **DR8.3:** Distinguishing herpes zoster and varicella from other skin lesions
- **DR8.4:** Distinguishing viral warts from other skin lesions
- **DR8.5:** Distinguishing molluscum contagiosum from other skin lesions
- **DR8.6:** Indications and procedure for the Tzanck smear
- **DR8.7:** Indications and pharmacology of antiviral therapy
Frequently Asked Questions
What does a Tzanck smear show in herpes?
A smear taken from the floor of a freshly deroofed vesicle shows multinucleated giant cells, which support a diagnosis of herpes simplex, varicella or zoster.
What is Hutchinson's sign?
Vesicles on the tip or side of the nose in herpes zoster, indicating nasociliary nerve involvement and a high risk of eye involvement, so ophthalmology review is needed.
When should molluscum contagiosum raise concern?
Widespread, giant or facial molluscum in an adult can be a marker of HIV infection and immunosuppression, so testing should be considered.
How are herpes infections treated?
Oral antivirals such as aciclovir, valaciclovir or famciclovir shorten and reduce the severity of herpes simplex and zoster, and work best when started early in the attack.
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