Molluscum Contagiosum

Molluscum contagiosum (MC) is caused by the DNA poxvirus Molluscum contagiosum virus (MCV). Among the four subtypes of MCV, MCV-1 is the most common. MC can be transmitted by direct and indirect contact, and prevalence is estimated at between 5% and 10% in the United States.

Risk factors for MC include atopic dermatitis and immune compromise. Transmission is most commonly via direct skin-to-skin contact and less commonly via fomites (e.g., towels, bath sponges). Other possible risk factors include activities with significant physical contact (e.g., wrestling, swimming pool use, sharing of towels within households, day care, and sexual intercourse with affected individuals).

Images and Clinical Manifestations

(Source: Molluscum Contagiosum. Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases [NCEZID], Division of High-Consequence Pathogens and Pathology [DHCPP], 2015.)

(Source: Molluscum Contagiosum in a Patient with the Acquired Immunodeficiency Syndrome. N Engl J Med 1998.)

• In the immunocompromised patient, consider the following alternative diagnoses for umbilicated papules:

  • histoplasmosis

  • penicilliosis

  • disseminated cryptococcosis

(Source: Disseminated Cryptococcosis. N Engl J Med 2014.)

Diagnosis

• The diagnosis is made clinically, by recognizing characteristic lesions on physical exam.

• If diagnosis is unclear by clinical exam, scraping of the lesion can help make the diagnosis (scrapings will have intracytoplasmic inclusion [molluscum] bodies with a Wright-Giemsa stain).

Treatment

• For immunocompetent patients, treatment is not necessary and is not associated with reduced time to resolution.

• Indications for treatment:

  • immunosuppression

  • superinfection

  • significant symptoms or immediate cosmesis concern

  • prevention of transmission in cases with genital involvement

• Nongenital lesions:

  • curettage may be more effective than medication therapy

  • cantharidin (applied in office every 2-4 weeks and washed off 4 hours later)

• Evidence suggests that imiquimod may not be as effective, particularly in children.

• Genital lesions:

  • cryotherapy (liquid nitrogen)

  • podophyllotoxin (0.5% topical cream twice daily 3 days per week for 4 weeks)

  • imiquimod (5% cream three times weekly for 16 weeks)