Self-limited poxvirus infection producing small dome-shaped umbilicated papules; common in children and immunocompromised adults.
Also known as: molluscum, molluscum contagiosum, MC
Overview
A common cutaneous infection caused by the Molluscum contagiosum virus (MCV), a double-stranded DNA poxvirus. Produces small, dome-shaped, flesh-colored to pearly-white umbilicated papules.
Epidemiology
Worldwide distribution; ~5% prevalence in children. Peak ages 2-5 years and sexually active young adults. Increased prevalence and severity in atopic dermatitis and HIV/immunocompromised.
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Question 1DermatologyMedium
A 28-year-old male has multiple firm, flesh-colored papules with central umbilication scattered over his trunk, arms, and face — some are larger than 1cm. CD4 is 45. He has no HIV treatment currently. Which of the following is the most likely diagnosis?
AMolluscum contagiosum
BCryptococcal skin lesions
CFolliculitis
DCondyloma acuminata
Reveal answer & full explanation
Correct answer: A — Molluscum contagiosum
AMolluscum contagiosum✓
BCryptococcal skin lesions
CFolliculitis
DCondyloma acuminata
Why Molluscum contagiosum is correct
Molluscum contagiosum is a poxvirus transmitted by skin-to-skin contact or fomites
In immunocompetent hosts it appears as 3-6mm dome-shaped umbilicated papules, self-limited over 6-18 months
In AIDS (CD4 below 50): widespread, confluent, and giant lesions (above 1cm) resistant to local therapy — as seen in this patient
Diagnosis is clinical (central umbilication) or by Giemsa/H&E stain showing Henderson-Patterson bodies (viral inclusion bodies)
Why the others are wrong
Cryptococcal skin lesions — can mimic molluscum but would be confirmed by culture or staining for encapsulated yeast, not Henderson-Patterson bodies (confused-with mimic)
Folliculitis — presents as follicular-based pustules, not umbilicated papules (right-region-wrong-lesion)
Condyloma acuminata — HPV-related genital/perianal warts, not dome-shaped umbilicated papules scattered over trunk, arms, and face (confused-with wart)
Additional high-yield points
Treatment: (1) antiretroviral therapy (ART) is most effective — immune reconstitution leads to spontaneous resolution; (2) local therapies: cryotherapy, curettage, trichloroacetic acid, cantharidin (blistering agent — most effective topical), potassium hydroxide; imiquimod is less effective in immunocompromised
Without immune restoration (ART), local treatments have high recurrence rates
Facial molluscum in an HIV patient is often a clinical marker of CD4 below 200 — AIDS-defining in widespread disease
Question 2DermatologyMedium
A 4-year-old boy is brought in by his mother, who noticed several small bumps on his trunk and right axilla over the past 6 weeks. He is otherwise healthy, attends daycare, and takes no medications. He has no pain or itching. On examination there are about eight discrete 2-4 mm dome-shaped, flesh-colored papules with central umbilication; the surrounding skin is normal and there is no erythema or drainage. The lesions spare the palms, soles, face, and genitals. Which of the following is the most appropriate initial management?
AActive observation and reassurance
BIn-office cantharidin application
CCurettage of each individual lesion
DCryotherapy with liquid nitrogen
Reveal answer & full explanation
Correct answer: A — Active observation and reassurance
AActive observation and reassurance✓
BIn-office cantharidin application
CCurettage of each individual lesion
DCryotherapy with liquid nitrogen
Why Active observation and reassurance is correct
Molluscum contagiosum is a self-limited poxvirus infection that resolves spontaneously in healthy children, typically within 6-12 months without scarring.
This child has few, asymptomatic, uncomplicated lesions and no immunocompromise, so watchful waiting plus parental reassurance is the evidence-based first-line approach.
Active intervention is reserved for symptomatic, extensive, cosmetically distressing, or anogenital lesions, or for immunocompromised hosts.
Why the others are wrong
In-office cantharidin application is a legitimate and often-preferred pediatric destructive therapy, but it is a step beyond what an asymptomatic well child with a handful of lesions needs initially.
Cryotherapy with liquid nitrogen is a real molluscum treatment, but it is painful, poorly tolerated by young children, and carries hypopigmentation and scarring risk.
Curettage of each individual lesion removes lesions immediately and is a valid option, but it is painful, usually requires topical anesthesia, and carries a small scarring risk.
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Children in close contact (daycare, siblings, swimming pools, shared towels)
Atopic dermatitis (impaired barrier, autoinoculation through scratching)
Sexual contact (genital molluscum in adults)
Immunosuppression — HIV (particularly when CD4 <100), transplant, biologics; lesions can become large, numerous, and refractory
Wrestlers, swimmers, gym users
Pathophysiology
MCV is the only poxvirus that infects humans without systemic spread. Infects keratinocytes through microabrasions; replicates entirely in the cytoplasm. Forms characteristic intracytoplasmic inclusion bodies (Henderson-Patterson 'molluscum bodies'). Spread by direct skin contact, fomites, and autoinoculation; incubation 2-7 weeks (range 1 week to 6 months).
Clinical presentation
Symptoms
Usually asymptomatic; cosmetic concern
Pruritus from associated dermatitis around lesions ('molluscum dermatitis')
Tenderness if secondarily infected (BOTE — beginning of the end — sign: erythema and inflammation precedes spontaneous resolution)
Signs / physical exam
Discrete 2-5 mm (occasionally up to 1-2 cm 'giant molluscum') dome-shaped flesh-colored to pearly-white papules with central umbilication (depression containing white waxy core)
Distribution in children: trunk, axillae, antecubital and popliteal fossae, face; spares palms and soles
Distribution in adults: genitalia, lower abdomen, inner thighs (sexually transmitted), or face (after shaving — autoinoculation)
Clinical: characteristic umbilicated papules; dermoscopy and histology in atypical cases.
Labs
Clinical diagnosis sufficient in most cases
Dermoscopy: central polylobular yellow-white amorphous structure with crown vessels
Expression of core onto slide with KOH or stain (Wright, Giemsa) shows Henderson-Patterson bodies
Biopsy if atypical, atypical site (palms/soles), or to exclude cryptococcosis in HIV
HIV testing in adults with extensive or facial molluscum without clear risk factor
Imaging
Not indicated
Diagnostic algorithm
Setting
Approach
Healthy child, asymptomatic
Active observation — resolves in 6-12 months
Bothersome / cosmetic / autoinoculating
Cantharidin in office; curettage; berdazimer gel
Adult genital molluscum
Treat lesions + screen STIs + counsel partner
Eyelid involvement
Refer ophthalmology before destructive therapy
Immunocompromised / HIV
Optimize ART; multimodal therapy; biopsy to exclude cryptococcosis
Molluscum contagiosum management by clinical setting.
Treatment
First-line
Active observation — molluscum is self-limited and resolves spontaneously in healthy children within 6-12 months (occasionally up to 4 years); no scarring
Cantharidin 0.7% in office — applied to each lesion, covered with tape, washed off in 2-6 hours; produces blister and resolution; well-tolerated in children (avoid face and genitals)
Berdazimer 10.3% topical gel — FDA-approved 2024 for ages ≥1 year; applied daily × up to 12 weeks
Cryotherapy (light liquid nitrogen) — quick, can be painful, hypopigmentation risk in skin of color
Curettage — removes lesion immediately; topical anesthetic before; small risk of scarring
Topical retinoids (tretinoin 0.05%) for flat lesions
KOH 10% topical (some studies show efficacy)
Imiquimod 5% has shown disappointing results in pediatric trials and is no longer recommended
Treat associated eczematous dermatitis with low-mid potency topical corticosteroid
Sexually transmitted (adult genital)
Same modalities as cutaneous, plus screen and treat partners
Counsel on condom use (incomplete protection)
Screen for other STIs
Immunocompromised (HIV, CD4 <100)
Initiate or optimize antiretroviral therapy — single most effective intervention
Combine destructive techniques (curettage, cryotherapy) with topical/systemic agents
Rule out cryptococcosis and other disseminated mycoses in atypical lesions
Second-line / adjunct
Intralesional candida antigen, interferon, or cidofovir (topical or IV) for refractory disease in immunocompromised
Hygiene counseling: avoid sharing towels, swimsuits, baths until resolved; do not pick or scratch lesions
Complications
Bacterial superinfection from scratching
Scarring (rare; mostly from destructive treatment)
Post-inflammatory hyper/hypopigmentation
Eyelid involvement → conjunctivitis or keratitis (refer to ophthalmology)
Extensive disease as marker of HIV/immunosuppression
Eczematous molluscum dermatitis and reactive id reactions
Sexual transmission stigma and partner concerns in adults
PANCE pearls
Umbilicated dome-shaped flesh-colored papules in a child = molluscum until proven otherwise.
BOTE sign (beginning of the end) — sudden inflammation, erythema, and crusting of a molluscum lesion heralds spontaneous resolution; do not treat as bacterial infection.
Numerous, large, or facial molluscum in an adult should prompt HIV testing — and consider cryptococcosis if CD4 <100.
Cantharidin is the preferred in-office treatment in pediatrics — painless on application, blister forms hours later.
Active observation is appropriate and evidence-based for healthy children; aggressive treatment is rarely required.
References
AAD 2023 — Management of Molluscum Contagiosum (AAD work group review)
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