Molluscum Contagiosum

Molluscum contagiosum is a common, annoying, and unimportant type of viral wart that goes away by itself if left alone. Two things lend it greater importance in people’s minds than it typically deserves:

1.    The assertions that molluscum is contagious and in adults is often sexually-transmitted; and
2.    The claimed association between having numerous mollusca and suffering from a suppressed immune system or HIV-AIDS.

To immediately correct these assumptions, in fact, very few patients with molluscum contagiosum have anyone in their vicinity with mollusca.  Although they may be contagious, ie, they have come from some viral source, where a patient may have gotten it is anybody’s guess, which is no more surprising than the fact that many people with common warts, caused by a different virus (Human Papilloma Virus [HPV]), also don’t seem to have caught them from anyone in particular.

As for immune suppression, children and adults who are perfectly healthy often get large numbers of mollusca.  Unless there is some particular reason to suspect immune problems in a molluscum patient, there is no need to look for internal problems.  Nowadays, many patients with HIV have their immune response under tight control with medications, making it far less common for them to develop the thousands of mollusca shown on some Web sites. (e.g. http://www.cehjournal.org/extra/53_05_01.html)

What causes molluscum contagiosum?

Molluscum warts are caused by a poxvirus.  Ordinary warts (common warts, plantar warts, genital warts) are caused by the Human Papilloma Virus), a completely different viral family.

What do mollusca look like? 

Molluscum lesions are small, round bumps that look waxy and measure 1-6 millimeters in size.  Larger mollusca have a small pit in the center (“umbilication,” meaning “having a navel”).  It is harder to see the pit in smaller mollusca unless they are frozen with liquid nitrogen, which is one of the common treatments for this disorder.  (See below)  Sometimes mollusca become red, swollen, and inflamed.  Rather than an indication that they are infected with bacteria, this change usually means that the mollusca are going away.

 

 

 

Young children often get mollusca on their chest and under their arms, but this condition can affect the legs, groin, or most anywhere.  Adults commonly get mollusca in the groin, which leads to the assumption that they must be sexually transmitted.  At times there may be a single, large molluscum in an unusual place, like the face.

Some patients, especially children with a tendency to have eczema, get patches of dermatitis (inflamed skin) around the molluscum lesions.

How are mollusca diagnosed?

Experienced physicians recognize most cases of molluscum contagiosum just by looking at them.  Freezing mollusca with liquid nitrogen can highlight pits if the bumps are small and pits hard to see.  In uncommon cases, physicians may establish the diagnosis by performing a biopsy on what they thought could be a skin cancer or some other unrelated condition.

Is molluscum contagiosum contagious?  In adults, is molluscum an STD?

The most accurate answer to these question is: “Yes, sometimes it can be.”  As a clinician who has seen any number of patients of all ages with mollusca for 30 years, however, I must add that while molluscum may be contagious, most of the time nobody nearby has it.  (And mollusca are hard to miss on siblings and sexual contacts, especially when you look for them.)   In other words, it’s worth checking for a source of contagiousness, but there is no need to be surprised if none is found.  This is of special importance to adults with mollusca in the pubic area or on the genitals who do not deserve to be told that they “have an STD” when in fact they very well may not.    (Syphilis, by contrast, is always an STD, and is never contracted from the proverbial toilet seat.)

In cases where molluscum contagiosum isn’t contagious, where does it come from?

Good question.  I don’t know.  Colds are contagious too, though we often don’t know exactly where we caught them.

How is molluscum contagiosum treated?

This depends on the age of the patient and the location of the lesions.  Treatment methods include:

•    Destruction: liquid nitrogen cryosurgery, application of acids (like trichloroacetic acid), silver nitrate, or phenol, or cantharidin, a vesicant or blistering agent.  These work well, but can hurt a great deal.  Also, they often need to be repeated several times, as new mollusca appear between sessions.
•    Surgery: Molluscum lesions can be flicked off with a sharp instrument.  Topical anesthetic creams can make this more tolerable.  Unless there are very few mollusca, this technique is not often used.  (One implication: everyone feels a bit guilty when they pick at things, but picking at a molluscum may actually get rid of it.)
•    Topical applications: tretinoin (Retin-A), imiquimod (Aldara).  These hurt less but don’t work very well.
•    Tincture of time: Mollusca can take months or even a year or two to go away, but they always do.

Painful, destructive methods are not very suitable for children.  Pediatricians often counsel reassurance and waiting the mollusca out, an approach I endorse.  For the anxious, Aldara may help, and may be worth a try in some cases.

Cryosurgery is tolerable for most adults.  It represents a good choice for someone who wants to rid his or her groin of embarrassing bumps as soon as possible.

References:

•    New Zealand Dermnet, http://www.dermnetnz.org/viral/molluscum-contagiosum.html.  Sensible text and good pictures
•    The American Academy of Dermatology article: http://www.aad.org/public/publications/pamphlets/viral_mollscum.html.  More emphasis on contagiousness than I would make.  Good pictures.