Molluscum Contagiosum

Molluscum contagiosum can infect any part of the skin except the palms of the hands and soles of the feet.

The bumps are usually less than 1/4 inch (about 0.2 to 0.5 centimeters) in diameter, shaped like a dome, and have a tiny dimple in the center.

In children, the bumps occur most commonly on the face, trunk, arms, and legs. In adults, the bumps occur most commonly on the penis, vulva, or in the pubic area.

The bumps usually are not itchy or painful and may be discovered only coincidentally during a physical examination. However, the bumps can become very inflamed (resembling a boil) and itchy as the body fights off the virus. This inflammation may indicate that the bumps will soon disappear.

Doctors base the diagnosis of molluscum contagiosum on its appearance.

If doctors are unsure of the diagnosis, they may remove a sample of material from the skin and examine it under a microscope.

Most bumps disappear spontaneously in 6 to 9 months, but they can remain for 2 to 3 years.

People with bumps in the groin area that were presumably acquired sexually should be treated to prevent spread of the infection. Otherwise, no treatment of molluscum contagiosum is needed unless the growths are disfiguring or otherwise bothersome.

Doctors apply or prescribe trichloroacetic acid, podophyllotoxin (podofilox) in adults, tretinoin, tazarotene, or cantharidin for the bumps. These medications are applied for weeks or months.

The bumps also can be treated by freezing (cryotherapy), burning with a laser or electric current, or removing their core with a needle or sharp scraping instrument (curette).

Dermatologists often use combination therapy such as liquid nitrogen or cantharidin in the office and give people a retinoid cream to use at home. This form of therapy is typically successful, but in some people the bumps often take 1 to 2 months to go away.

Other treatments include injection of Candida antigen into a bump and photodynamic therapy. Candida antigens are proteins that come from the Candida yeast. When injected into the bump, they cause an immune response that fights against the virus. Similarly, interferons are proteins that trigger immune cells to attack the virus. In photodynamic therapy, a chemical preparation is applied to the skin and then artificial light is applied to the bumps. The light activates the chemical to produce a form of oxygen that kills the virus causing the bumps.

In people with HIV infection who develop molluscum contagiosum, treatment of the HIV infection with antiviral medications is often necessary to allow the molluscum contagiosum to resolve.

Children do not need to be excluded from school or day care. However, their bumps should be covered to reduce the risk of spread to others.