|Classification and external resources|
Typical flesh-colored, dome-shaped and pearly lesions
Molluscum contagiosum (MC) is a viral infection of the skin or occasionally of the mucous membranes, sometimes called water warts. It is caused by a DNA poxvirus called the molluscum contagiosum virus (MCV). MCV has no nonhuman-animal reservoir (infecting only humans). There are four types of MCV, MCV-1 to -4; MCV-1 is the most prevalent and MCV-2 is seen usually in adults. The virus that causes molluscum is spread from person to person by touching the affected skin. The virus may also be spread by touching a surface with the virus on it, such as a towel, clothing, or toys. Once someone has the virus, the bumps can spread to other parts of their body by touching or scratching a bump and then touching another part of the body. Molluscum can be spread from one person to another by sexual contact. This common viral disease has a higher incidence in children, sexually active adults, and those who are immunodeficient, and the infection is most common in children aged one to ten years old. MC can affect any area of the skin but is most common on the trunk of the body, arms, groin, and legs. It is spread through direct contact or shared items such as clothing or towels. There is evidence that molluscum infections have globally been on the rise since 1966, but these infections are not routinely monitored because they are seldom serious and routinely disappear without treatment. The virus commonly spreads through skin-to-skin contact. This includes sexual contact or touching or scratching the bumps and then touching the skin. Handling objects that have the virus on them (fomites), such as a towel, can also result in infection. The virus can spread from one part of the body to another or to other people. The virus can be spread among children at day care or at school. Molluscum contagiosum is contagious until the bumps are gone. Some growths may remain for up to 4 years if not treated.
Signs and symptoms
Molluscum contagiosum lesions are flesh-colored, dome-shaped, and pearly in appearance. They are often 1–5 millimeters in diameter, with a dimpled center. They are generally not painful, but they may itch or become irritated. Picking or scratching the bumps may lead to further infection or scarring. In about 10% of the cases, eczema develops around the lesions. They may occasionally be complicated by secondary bacterial infections. In some cases the dimpled section may bleed once or twice. The viral infection is limited to a localized area on the topmost layer of the epidermis. Once the virus-containing head of the lesion has been destroyed, the infection is gone. The central waxy core contains the virus. In a process called autoinoculation, the virus may spread to neighboring skin areas. Children are particularly susceptible to autoinoculation, and may have widespread clusters of lesions.
Individual molluscum lesions may go away on their own and are reported as lasting generally from 6 weeks, to 3 months. The lesions may propagate via autoinoculation so an outbreak generally lasts longer. Mean durations for an outbreak are variously reported from 8 months to about 18 months, but durations are reported as widely as 6 months to 5 years, lasting longer in immunosuppressed individuals.
|Molluscum contagiosum virus|
|EM of Molluscum contagiosum virus|
|Group:||Group I (dsDNA)|
|Species:||Molluscum contagiosum virus|
Diagnosis is made on the clinical appearance; the virus cannot routinely be cultured. The diagnosis can be confirmed by excisional biopsy.
- abundant granular eosinophilic cytoplasm (accumulated virons), and
- a small peripheral nucleus.
Treatment options can often involve discomfort to the child so initial recommendations are often expectant management, simply waiting for the lesions to resolve spontaneously. Current treatment options are invasive, requiring tissue destruction and attendant discomfort. Currently there is no US licensed Molluscum contagiosum Vaccine, attempts have been made but it is difficult to instill a permanent immunity to the virus.
It should also be noted that treatments causing the skin on or near the lesions to rupture may spread the infection further, much the same as scratching does.
Bumps located in the genital area may be treated in an effort to prevent them from spreading. When treatment has resulted in elimination of all bumps, the infection has been effectively cured and will not reappear unless the person is reinfected.
Two randomized, placebo controlled clinical trials treating molluscum in children with a combination of essential oils have demonstrated the effectiveness in children with molluscum. The second, more recent study showed a 90% or greater reduction in the number of visible molluscum lesions in 16 of 19 children (84.2%) using a combination of essential oil of Melaleuca alternifolia (tea tree oil) and organically bound iodine  . Tea tree oil alone worked for only 18% of children.
For mild cases, over-the-counter wart medicines, such as salicylic acid may or may not shorten infection duration. Daily topical application of tretinoin cream may also trigger resolution. These treatments require several months for the infection to clear, and are often associated with intense inflammation and possibly discomfort.
Imiquimod may be used. Imiquimod is a form of immunotherapy. Immunotherapy triggers the immune system to fight the virus causing the skin growth. Imiquimod is applied 3 times per week, left on the skin for 6 to 10 hours, and washed off. A cure may take from 4 to 16 weeks. Another dose regimen: apply imiquimod three times daily for 5 consecutive days each week.
Surgical treatments include cryosurgery, in which liquid nitrogen is used to freeze and destroy lesions, as well as scraping them off with a curette. Application of liquid nitrogen may cause burning or stinging at the treated site, which may persist for a few minutes after the treatment. Scarring or loss of color can complicate both these treatments. With liquid nitrogen, a blister may form at the treatment site, but it will slough off in two to four weeks. Although its use is banned by the FDA in the United States in its pure, undiluted form, the topical blistering agent cantharidin can be effective. Cryosurgery and curette scraping are painless procedures. They may also leave scars and/or permanent white (depigmented) marks.
Most cases of molluscum will clear up naturally within two years (usually within nine months). So long as the skin growths are present, there is a possibility of transmitting the infection to another person. When the growths are gone, the possibility for spreading the infection is ended.
Unlike herpes viruses, which can remain inactive in the body for months or years before reappearing, molluscum contagiosum does not remain in the body when the growths are gone from the skin and will not reappear on their own. However, there is no permanent immunity to the virus, and it is possible to become infected again upon exposure to an infected person.
Advantage of treatment is to hasten the resolution of the virus. This limits the size of the "pox" scar. If left untreated, molluscum growth can reach sizes as large as a pea or a marble. Spontaneous resolution of large lesions can occur, but will leave larger crater like growth. As many treatment options are available, prognosis for minimal scarring is best if treatment is initiated while lesions are small.
Approximately 122 million people were affected by molluscum contagiosum as of 2010 (1.8% of the population).
- Acrochordons (also called skin tags — similar in appearance and grow in similar areas)
- Umbilicated lesions
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|Wikimedia Commons has media related to: Molluscum contagiosum|
- Molluscum Center for Disease Control
- Virus Pathogen Database and Analysis Resource (ViPR): Poxviridae