Molluscum contagiosum

Molluscum contagiosum is a common skin infection caused by the molluscum contagiosum virus and typically manifests on the trunk, face, and genitalia. Molluscum contagiosum is most common in childhood and early adolescence and is usually transmitted in this age group via skin contact and autoinoculation. In adults, it is often sexually transmitted. Lesions typically manifest as smooth, dome-shaped papules with central umbilication, localized on the trunk and face in children and lower abdomen and groin in adults. Molluscum contagiosum is usually self-limiting and resolves spontaneously within 1 year. Treatment may be indicated for symptomatic control, cosmesis, infection control, and in immunosuppressed individuals with widespread, persistent lesions. Cryotherapy, curettage, and topical cantharidin are the preferred treatment options. Isolation precautions are usually not indicated as the risk of transmission is typically low.

• Sex: ♂ > ♀
• Age: most common in childhood (peak incidence < 5 years of age) and early adolescence
• Prevalence
  • More common in warm and humid climates or areas with poor hygiene
  • More common in immunocompromised individuals; up to 20% of HIV-positive patients have symptomatic infection. ^[1]

Epidemiological data refers to the US, unless otherwise specified.

• Pathogen: molluscum contagiosum virus (a DNA poxvirus)
• Transmission ^[2]
  • Direct skin contact (e.g., through contact sports, sexual contact)
  • Autoinoculation (from scratching, shaving, or touching)
  • Fomites (e.g., on bath sponges or towels)
  • Vertical transmission
• Incubation period: typically 2–7 weeks ^[1][2]

• Appearance ^[2]
  • Solitary or multiple nontender, skin-colored, pearly, dome-shaped papules with central umbilication
  • Usually 2–5 mm in diameter
  • Possible perilesional pruritic eczematous reaction (molluscum dermatitis) ^[1][2]
• Typical distribution ^[1][2]
  • In children: face, trunk, and extremities
  • In adults or in sexually transmitted cases: lower abdomen, groin, genitalia, and proximal thighs

Lesions are often widespread, large, and persistent in immunocompromised patients and those with atopic dermatitis. ^[2][3][4]

• Diagnosis is primarily clinical; dermoscopy can aid visualization. ^[1][2]
• If there is diagnostic uncertainty, consider:
  • Skin biopsy: Molluscum bodies on histopathology confirm the diagnosis. ^[1][2]
  • NAAT testing (if available) ^[2]
• Atypical or extensive spread: Consider evaluation for underlying immunocompromising conditions (e.g., HIV testing).
• Genital lesions in sexually active patients: Screen for other STIs (see “STI screening”). ^[2]

Genital lesions in children are usually caused by autoinoculation and do not necessarily indicate sexual abuse. ^[1][2]

Histology ^[5]

• Localized to the epidermis
• H&E-stained sections demonstrate the following
  • Acanthosis (thickened epidermis)
  • Cup-shaped invagination (the epidermis invaginates into the dermis)
  • Molluscum bodies: keratinocytes with eosinophilic intracytoplasmic inclusion bodies containing viral particles

• Cutaneous warts
• Anogenital warts
• Condylomata lata
• Mpox
• Shingles
• Scabies
• Chickenpox
• Folliculitis
• Milia
• Cutaneous cryptococcosis
• Cutaneous histoplasmosis
• Cutaneous aspergillosis
• Keratoacanthoma

The differential diagnoses listed here are not exhaustive.

General principles ^[1][2]

• Expectant management is usually sufficient for immunocompetent children.
  • Advise patients and caregivers that lesions typically resolve spontaneously within 1 year. ^[2][4]
  • Recommend infection control measures.
• Indications for treatment of molluscum contagiosum lesions include: ^[1][2]
  • Extensive spread (e.g., in immunocompromised individuals)
  • Complications (e.g., secondary bacterial infection)
  • Infection control (e.g., sexually active individuals with genital lesions)
  • Symptomatic control (e.g., pruritus)
  • Cosmesis
• Treat underlying and associated conditions as indicated, e.g.,
  • Management of atopic dermatitis and symptomatic molluscum dermatitis ^[6][7]
  • Optimization of antiretroviral therapy in patients with HIV ^[4][8]

Infection control measures ^[1][2]

Measures that can reduce the possibility of spread to others include avoidance of:

• Scratching, shaving over, or picking at lesions
• Sharing towels or bed linen
• Skin-to-skin contact (cover lesions during contact sports and swimming)

Isolation precautions are not indicated for patients with molluscum contagiosum as the risk of transmission is usually low. Children may attend school or daycare and participate in sports. ^[2]

Initial treatment options ^[1][9]

• There is no consensus on molluscum contagiosum treatment.
• Educate patients that most treatment options cause pain, scarring, blistering, and pigment changes.

Cryotherapy, curettage, and topical cantharidin are typically the most effective treatment options but require multiple sessions and should be administered by a healthcare professional. ^[1][9]

Physical destruction

Physical destruction often requires local anesthesia, especially in young children.

• Cryotherapy
• Curettage
• Electrodesiccation
• Laser

Topical agents for chemical destruction

• Topical cantharidin (in individuals ≥ 2 years of age) ^[1][2]
• Berdazimer gel (in individuals ≥ 1 year of age) ^[10]
• Other agents: podophyllin, tretinoin, trichloroacetic acid, potassium hydroxide ^[1][2]

Cantharidin should be applied by a trained healthcare professional due to the risk of adjacent tissue damage if incorrectly applied.

Treatment of severe or refractory disease ^[1][2]

• Refer to dermatology.
• Cidofovir may be considered in immunocompromised individuals with severe or refractory lesions.

The antiviral agent cidofovir should be reserved for severe disease (e.g., in immunocompromised patients) due to its adverse risk profile. ^[2]

• Dermatitis (molluscum dermatitis, atopic dermatitis flare) ^[9]
• Bacterial superinfections ^[1]
• Molluscum contagiosum conjunctivitis ^[11]

We list the most important complications. The selection is not exhaustive.