Molluscum contagiosum

Q Our two-year-old twins have red bumps on their arms and thighs. We tried scrubbing the areas but the skin only became sore.

A They have molluscum contagiosum, (MC) a viral infection, similar in scope to the common wart. The small globular lesions, which look like M&M's attached to the skin, are caused by a large double-stranded DNA virus of the poxvirus family.

MC is often found on arms and legs but may also be seen on the abdomen, armpits, and neck. The dome-shaped lesions are two to five millimeters in diameter. MC does not create much of an inflammatory response; however, when the child scratches or rubs the area, the surrounding area becomes irritated with redness, scaling, and even oozing.

The MC virus is spread by personal contact and disappears, without treatment, in about two years. The incubation period seems to be between one and eight weeks, so treating the source is just a guess.

For a long time, young children were the only ones to have MC, but within recent years, older children and young adults are also bothered by these slightly itchy bumps.

This benign condition might be confused with the common wart. When the area is scratched and becomes irritated, the area may look like contact dermatitis or atopic dermatitis. Applying topical cortieosteroids will reduce the irritation, but they will not make a MC go away. If this happens, it points to the diagnosis of MC.

As in any viral condition of the skin, there are many suggested treatments. Once the surrounding irritation is brought under control with topical steroids, the treatment of the viral infection can be considered. Unlike warts, MC infections seem to last no more than two years and almost never recur.

I prefer to use a keratolytic--wart medicine to peel down the skin. Once the top of the lesion is exposed, globules fall away and that is the end of the MC infection. Imiquimod cream, applied three times a week for three months, also seems to be useful. Duet tape can be applied to destroy the lesions or a cantharidin preparation can be used. If the child will tolerate a surgical procedure, the MC lesion can be snipped or frozen with liquid nitrogen.

MC can be considered a nuisance that will eventually disappear. As with most viral diseases, there is no systemic treatment. Once the lesions do dissolve, a new attack is unlikely to occur.

Lawrence Charles Parish, M.D., is a clinical professor of Dermatology and Cutaneous Biology and director of the Jefferson Center for International Dermatology, Jefferson Medical College, Philadelphia, PA.

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