Molluscum contagiosum

Definition
Molluscum contagiosum is a viral skin infection that causes raised, pearl-like papules or nodules on the skin.

Causes, incidence, and risk factors

Molluscum contagiosum is caused by a virus that is a member of the Poxvirus family. This virus is called Molluscipoxvirus Molluscum contagiosum.

This is a common infection in children. It is frequently seen on the face, neck, arm pit, arms, and hands but may occur anywhere on the body except the palms and soles. Occasionly, it is seen on the genitals.

In adults, molluscum is generally seen on the genitals as a sexually-transmitted disease. Because molluscum produces no serious illness and is not of long-term public health significance, it has not been treated as other sexually-transmitted diseases. The importance is significant in the growing population of immunocompromised people with AIDS, who may develop a fulminating (rapidly worsening) case of molluscum contagiosum.

Typically, the lesion of molluscum begins as a small papule which may become raised up to a pearly, flesh-colored nodule. The papule often has a dimple in the center (umbilication). These papules may occur in lines, where the person has scratched. Scratching or other irritation causes the virus to spread in a line or in groups (crops).

The papules are approximately 2 to 5 millimeters in diameter and painless. There is usually no inflammation and subsequently no redness unless the person has been digging or scratching at the lesions. In the mature molluscum, the top of the nodule may be opened with a sterile needle and a small waxy core can be seen and squeezed out of the lesion.

Molluscum contagiosum is a chronic infection and lesions may persist from a few months to a few years. These lesions ultimately disappear without scarring. Early lesions on the genitalia may be mistaken for herpes or warts but, unlike herpes, these lesions are painless.

The virus is contagious through direct contact, as seen in children, but may spread by sexual contact. It can spread on a person from lesions to adjacent normal skin areas.

Symptoms
The skin lesion commonly has the following qualities:

     
  • small (2 to 5 millimeter diameter)  
  • dimple in center  
  • initially firm, flesh-colored, pearl-like, dome-shaped  
  • later lesions become softer, gray, and may drain  
  • central core or plug of white, cheesy or waxy material  
  • painless  
  • single or multiple (usually multiple)  
  • common locations in children: face, trunk, limbs  
  • common locations in adults: genitals, abdomen, inner thigh

Signs and tests
Diagnosis is based on the appearance of the lesion and can be confirmed by a skin biopsy. The health care provider should examine the lesion to rule out other disorders and to determine other underlying disorders.

Treatment
In people with normal immune systems, the disorder usually disappears spontaneously over a period of months to years. The lesions may be extensive in people with AIDS or other conditions that affect the immune system. Individual lesions may be removed surgically, by scraping, de-coring, freezing, or through needle electrosurgery. Surgical removal of individual lesions may result in scarring. Medications, such as those used to remove warts, may be helpful in removal of lesions.

Expectations (prognosis)
Individual lesions of molluscum contagiosum usually disappear within about 2 to 3 months. Complete disappearance of all lesions generally occurs within about 6 to 18 months. The disorder may persist in immunosuppressed people.

Complications

     
  • persistence, spread, or recurrence of lesions  
  • secondary bacterial skin infections

Calling your health care provider
Call for an appointment with your health care provider if you have symptoms suggestive of molluscum contagiosum. Also call for an appointment with your health care provider if lesions persist or spread, or if new symptoms appear.

Prevention

Avoid direct contact with the skin lesions.

Total abstinence is the only fullproof way of avoiding molluscum virus and other STDs. You can also avoid STDs by having a monogamous sexual relationship with a partner known to be disease-free.

Male and female condoms cannot fully protect you, as the virus can be on areas not covered by the condom. Nonetheless, condoms should still be used every time the disease status of a sexual partner is unknown. They reduce your chances of getting or spreading STDs. Use them with spermicide with nonoxynol 9.

Johns Hopkins patient information

Last revised: December 3, 2012
by Martin A. Harms, M.D.

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