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)