Definition
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Molluscum contagiosum (MC): a benign, self-limiting viral skin infection caused by molluscum contagiosum virus (MCV), a poxvirus.
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Characterized by small, flesh-colored, dome-shaped papules with central umbilication.
Epidemiology & Risk Factors
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Common in children aged 1–10 years, sexually active adults, and immunocompromised patients (e.g., HIV).
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Highly contagious via direct skin-to-skin contact or fomites (towels, clothing).
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Incubation period: 2–8 weeks.
Clinical Features
| Feature | Description | High-Yield Points |
|---|---|---|
| Lesions | 2–5 mm, firm, dome-shaped, pearly/flesh-colored papules | Central umbilication is characteristic |
| Distribution | Children: face, trunk, limbs; Adults: genital area (sexually transmitted) | Linear arrangement may indicate autoinoculation |
| Number | Often multiple; may coalesce | Can be a clue to immunodeficiency if extensive |
| Symptoms | Usually asymptomatic | Mild pruritus possible; secondary infection rare |
💡 Exam Tip: Central umbilication = classic diagnostic clue.
Differential Diagnosis
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Warts (verruca vulgaris) – rough surface, no central dimple
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Keratoacanthoma – larger, rapid growth, dome-shaped
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Folliculitis – pustular, not pearly
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Basal cell carcinoma – usually solitary, pearly, telangiectasia, not umbilicated
Investigations
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Usually clinical diagnosis; rarely biopsy.
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Histology (if needed): molluscum bodies (Henderson-Patterson bodies) in keratinocytes.
Management
General Measures
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Often self-limiting: resolves in 6–12 months in immunocompetent children.
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Avoid scratching and sharing towels.
Active Treatment (if lesions symptomatic, extensive, or cosmetically concerning)
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Physical removal: curettage, cryotherapy, laser therapy.
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Topical therapy:
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Cantharidin
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Podophyllotoxin (for genital lesions)
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Imiquimod (less commonly used)
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Immunocompromised Patients
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May require more aggressive therapy; lesions can be persistent and extensive.
Complications
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Secondary bacterial infection if scratched
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Rare scarring from treatment
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Cosmetic concern or psychosocial impact
PLAB-Style Questions
Q1: A 5-year-old child presents with multiple 3 mm flesh-colored papules with central umbilication on the trunk and arms. They are asymptomatic. Most likely diagnosis?
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A. Verruca vulgaris
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B. Molluscum contagiosum
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C. Basal cell carcinoma
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D. Folliculitis
✅ Answer: B. Molluscum contagiosum
Q2: In which patient would Molluscum contagiosum lesions most likely be extensive and persistent?
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A. Healthy 6-year-old child
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B. Teenager with mild eczema
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C. Adult with HIV infection
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D. Adult with mild sunburn
✅ Answer: C. Adult with HIV infection
(Immunocompromised patients often have widespread, persistent lesions.)
High-Yield Pearls
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MC = flesh-colored, dome-shaped papules with central umbilication.
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Usually self-limiting in children; active treatment optional.
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Spread via direct contact or fomites; prevent autoinoculation.
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Immunocompromised patients may require aggressive therapy.
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Diagnosis is clinical; biopsy rarely needed.
