Molluscum Contagiosum

Molluscum contagiosum (MC) is a skin rash caused by a virus first described in 1817. It is a member of the Poxvirus family. It is common worldwide and accounts for about 1% of all skin disorders in the United States. It primarily affects children (boys more often than girls) and young adults. Overall, the incidence of molluscum contagiosum is increasing.

Molluscum Contagiosum Causes
A person can contract molluscum contagiosum primarily by direct contact, either person-to-person or by shared items, such as clothing, towels, and washcloths. MC can be spread by touching the rash and then another part of the body. Although the likelihood of infection is generally low, it is unknown how long a person is contagious.

Outbreaks have occurred in the following settings:
■  Swimming pools (in children)
■  Wrestling matches
■  During surgery, by a surgeon with a hand lesion
■  Via tattoos (although rarely)
■  Sexually: It is likely that genital lesions are sexually transmitted. Lesions develop within 2-3 months after exposure. Not all genital lesions in adults are sexually transmitted, however. Check children with MC involving the genitals for possible sexual abuse. Genital lesions in children, however, do not always mean that sexual abuse has occurred. No cases of MC contracted from exposure to a contaminated toilet seat have been reported. Although theoretically possible, this means of transmission would appear to be extremely rare.

Molluscum Contagiosum Symptoms
After an incubation period of 2-7 weeks, a molluscum contagiosum rash begins as tiny papules (small raised bumps), each measuring 3-6 mm (about one-eighth to one-quarter inch). Some lesions may be as large as 3 cm (1.2 inches) across.

■  The MC rash appears as smooth, pearly to flesh-colored, dome-shaped papules initially. With time, the center becomes soft and indented (umbilicated) with a white curdlike core. This core may be squeezed out easily. Some redness and scaling are possible at the edges of a lesion. This may be the result of inflammation or from scratching.
■  Lesions may be located on any area of the skin and on mucous membranes. They are usually grouped in 1 or 2 areas, but may be widely spread. Most commonly, they are located on the face, eyelids, neck, underarms, and thighs. Adults often get them in the genital area. Usually, fewer than 20 lesions appear, but several hundred are possible.
■  The rash only rarely involves the mouth, palms, or soles.
■ The rash usually causes no itching or tenderness. There are no generalized symptoms such as fever, nausea, or weakness.

When to Seek Medical Care
Sometimes the lesions can become irritated, inflamed, and infected by bacteria. If this occurs, consult a doctor to discuss the need for antibiotics.
■  Lesions involving the eyelids may be associated with conjunctivitis (pinkeye) and require special treatment.

Exams and Tests
The doctor usually diagnoses molluscum contagiosum based on its distinctive appearance. For most cases, no tests are necessary.
■  The diagnosis can be confirmed by squeezing the core of a lesion onto a slide for examination, or by getting a biopsy if the diagnosis is uncertain.
■  Conditions that can mimic MC include some skin cancers, warts, infections, and a number of other skin conditions.

Medical Treatment
Treatment for molluscum contagiosum is not always mandatory. The lesions often disappear by themselves and heal without scarring unless infected by bacteria. Removal of lesions reduces the rate of spread to other people as well as from one part of the body to another, which happens by touching the lesions (called autoinoculation). Genital lesions in adults should be treated in order to prevent spread through sexual contact.

The most popular treatments are scraping of the lesions (called curettage), or removal using heat (called cautery) or cold (called cryotherapy, and performed with liquid nitrogen).

Medications
Your doctor may prescribe creams to be applied to the lesions:
■  Trichloroacetic acid
■  Topical podophyllotoxin cream (such as Condylox), which is derived from plant resins
■  Cantharidin (Cantharone, obtained from a blister beetle), applied by the doctor
■  Imiquimod (Aldara), a topical cream that works by boosting the immune system - Although this drug is currently approved only for treatment of genital warts, it has been found to be effective against MC and can be applied at home.
■  Cimetidine (Tagamet), the antiulcer and antiheartburn medication - This drug has been reported to be useful in the treatment of MC. This is not officially approved by the FDA for the treatment of MC.

Follow-up
It is not necessary to keep children who are infected with molluscum contagiosum out of school, although physical contact and sharing of clothes and towels should be discouraged.

Prevention
Good personal hygiene is a key factor in avoiding transmission of this disease.
■  MC is spread by close personal contact with infected people. Avoid skin-to-skin contact with others in order to prevent transmission.
■  Transmission has been shown to occur in children from swimming pools and in the sharing of baths, towels, gym equipment, and benches.
■  Because the rash can spread by autoinoculation (spread from one part of the body to another by touching the lesions), avoid scratching the lesions.
■  Because sexual transmission is common in adults, avoid sexual contact with infected people. It is unclear whether condoms are effective in preventing spread of MC.

Outlook
The overall prognosis is excellent. Spontaneous cure is the rule in people who have intact immune systems, but the process may take months or even years.
■  Individual lesions may last 2-4 months, and the development of new lesions by autoinoculation is common.
■  Most cases go away by themselves in 6-12 months.
■ Those cases that last for years typically occur in people with impaired immune systems.
■  Reinfection can occur.