What is molluscum contagiosum

Molluscum contagiosum is an infection caused by a poxvirus (molluscum contagiosum virus) ¹⁾. The result of the infection is usually a benign, mild skin disease characterized by lesions (growths) that may appear anywhere on the body. Within 6-12 months, Molluscum contagiosum typically resolves without scarring but may take as long as 4 years.

Children aged 2–5 years are most commonly affected with molluscum contagiosum, although it can occur in adolescents and adults. It is rare in children aged younger than one year. Molluscum contagiosum is more prevalent in warm climates than cool ones, and in overcrowded environments.

Children with atopic eczema (atopic dermatitis) may be more severely affected by molluscum contagiosum due to the skin barrier breaks and immune cell dysfunction in atopic skin. In addition, these patients may be more likely to autoinoculate (excoriation of primary lesions and spread to areas of normal skin) new areas of skin because of the underlying pruritus from their atopy.

The lesions, known as Mollusca, are small, raised, and usually white, pink, or flesh-colored with a dimple or pit in the center. They often have a pearly appearance. They’re usually smooth and firm. In most people, the lesions range from about the size of a pinhead to as large as a pencil eraser (2 to 5 millimeters in diameter). They may become itchy, sore, red, and/or swollen.

• Whenever you can see the bumps on the skin, molluscum contagiosum is contagious.

Most people get about 10 to 20 bumps on their skin. If a person has a weakened immune system, many bumps often appear.

Mollusca may occur anywhere on the body including the face, neck, arms, legs, abdomen, and genital area, alone or in groups. The lesions are rarely found on the palms of the hands or the soles of the feet.

Molluscum contagiosum can be very extensive and troublesome in patients with human immunodeficiency virus (HIV) infection or that have other reasons for poor immune function.

Patients with HIV/AIDS and other immunocompromising conditions (e.g., solid organ transplant recipients) can develop “giant” lesions (≥15 mm in diameter), larger numbers of lesions (100 or more molluscum contagiosum bumps) and lesions that are more resistant to standard therapy. The following diseases should be considered in the differential diagnosis of molluscum contagiosum: cryptococcosis, basal cell carcinoma, keratoacanthoma, histoplasmosis, coccidioidomycosis, and verruca vulgaris. For genital lesions, condyloma acuminata and vaginal syringomas should be considered.

Molluscum contagiosum lesions have recently come to be classified in one of three ways:

• The commonly seen skin lesions found largely on the faces, trunks, and limbs of children;
• The sexually transmitted lesions found on the abdomen, inner thighs, and genitals of sexually active adults; and
• The diffuse and recalcitrant eruptions of patients with AIDS or other immunosuppressive disorders.

Treatment of mild molluscum contagiosum infections is often not required because lesions will eventually resolve on their own. However, you can decrease the chance of spreading the infection to other parts of your body or to other people with the following guidelines:

• Do not scratch or shave the affected areas.
• Avoid sharing clothing, towels, and bedding with others.
• If the affected area is small, keep it covered.

Figure 1. Molluscum contagiosum in children

Footnote: Each molluscum contagiosum starts out as a very small spot, about the size of a pinhead, and grows over several weeks into a larger bump that might become as large as a pea or pencil eraser. A tiny dimple (indentation) often develops on the top of each molluscum contagiosum.

What causes molluscum contagiosum?

Molluscum contagiosum is caused by a poxvirus, the molluscum contagiosum virus. There are at least 4 viral subtypes.

There are several ways the molluscum contagiosum virus can spread:

• Direct skin-to-skin contact
• Indirect contact via shared towels or other items
• Auto-inoculation into another site by scratching or shaving
• Sexual transmission in adults.

Transmission of molluscum contagiosum appears to be more likely in wet conditions, such as when children bathe or swim together. The incubation period is usually about 2 weeks but can be as long as 6 months.

How do people get molluscum contagiosum ?

The virus that causes molluscum spreads from direct person-to-person physical contact and through contaminated fomites. Fomites are inanimate objects that can become contaminated with virus; in the instance of molluscum contagiosum this can include linens such as clothing and towels, bathing sponges, pool equipment, and toys. Although the virus might be spread by sharing swimming pools, baths, saunas, or other wet and warm environments, this has not been proven. Researchers who have investigated this idea think it is more likely the virus is spread by sharing towels and other items around a pool or sauna than through water.

Someone with molluscum contagiosum can spread it to other parts of their body by touching or scratching a lesion and then touching their body somewhere else. This is called autoinoculation. Shaving and electrolysis can also spread mollusca to other parts of the body.

Molluscum contagiosum can spread from one person to another by sexual contact ²⁾. Many, but not all, cases of molluscum in adults are caused by sexual contact ³⁾.

Conflicting reports make it unclear whether the disease may be spread by simple contact with seemingly intact lesions or if the breaking of a lesion and the subsequent transferring of core material is necessary to spread the virus.

The molluscum contagiosum virus remains in the top layer of skin (epidermis) and does not circulate throughout the body; therefore, it cannot spread through coughing or sneezing ⁴⁾.

Since the virus lives only in the top layer of skin, once the lesions are gone the virus is gone and you cannot spread it to others ⁵⁾. Molluscum contagiosum is not like herpes viruses, which can remain dormant (“sleeping”) in your body for long periods and then reappear.

Who is at risk for molluscum contagiosum infection ?

Molluscum contagiosum is common enough that you should not be surprised if you see someone with it or if someone in your family becomes infected. Although not limited to children, it is most common in children 1 to 10 years of age.

People at increased risk for getting molluscum contagiosum include:

• People with weakened immune systems (i.e., HIV-infected persons or persons being treated for cancer) are at higher risk for getting molluscum contagiosum. Their growths may look different, be larger, and be more difficult to treat.
• Atopic dermatitis may also be a risk factor for getting molluscum contagiosum due to frequent breaks in the skin. People with this condition also may be more likely to spread molluscum contagiousm to other parts of their body for the same reason.
• People who live in warm, humid climates where living conditions are crowded.

In addition, there is evidence that molluscum contagiosum infections have been on the rise in the United States since 1966, but these infections are not routinely monitored because they are seldom serious and routinely disappear without treatment.

How can you prevent molluscum contagiosum from spreading ?

The best way to avoid getting molluscum contagiosum is by following good hygiene habits. Remember that the virus lives only in the skin and once the lesions are gone, the virus is gone and you cannot spread the virus to others.

Wash your hands

There are ways to prevent the spread of molluscum contagiosum. The best way is to follow good hygiene (cleanliness) habits. Keeping your hands clean is the best way to avoid molluscum infection, as well as many other infections. Hand washing removes germs that may have been picked up from other people or from surfaces that have germs on them.

Don’t scratch or pick at molluscum contagiosum lesions

It is important not to touch, pick, or scratch skin that has lesions, that includes not only your own skin but anyone else’s. Picking and scratching can spread the virus to other parts of the body and makes it easier to spread the disease to other people too.

Keep molluscum contagiosum lesions covered

It is important to keep the area with molluscum lesions clean and covered with clothing or a bandage so that others do not touch the lesions and become infected. Do remember to keep the affected skin clean and dry.

Any time there is no risk of others coming into contact with your skin, such as at night when you sleep, uncover the lesions to help keep your skin healthy.

Be careful during sports activities

Do not share towels, clothing, or other personal items.

People with molluscum contagiosum should not take part in contact sports like wrestling, basketball, and football unless all lesions can be covered by clothing or bandages.

Activities that use shared gear like helmets, baseball gloves and balls should also be avoided unless all lesions can be covered.

Swimming should also be avoided unless all lesions can be covered by watertight bandages. Personal items such as towels, goggles, and swim suits should not be shared. Other items and equipment such as kick boards and water toys should be used only when all lesions are covered by clothing or watertight bandages.

Swimming Pools

Parents and others often ask if molluscum virus can spread in swimming pools. There is also concern that it can spread by sharing swimming equipment, pool toys, or towels.

Some investigations report that spread of molluscum contagiosum is increased in swimming pools. However, it has not been proved how or under what circumstances swimming pools might increase spread of the virus. Activities related to swimming might be the cause. For example, the virus might spread from one person to another if they share a towel or toys. More research is needed to understand if and for how long the molluscum virus can live in swimming pool water and if such water can infect swimmers.

Open sores and breaks in the skin can become infected by many different germs. Therefore, people with open sores or breaks from any cause should not go into swimming pools.

If a person with molluscum contagiosum is going swimming, they should:

• Cover all visible lesions with watertight bandages
• Dispose of all used bandages at home
• Not share towels, kick boards, other equipment, or toys.

Day Care Centers and Schools

There is no reason to keep a child with molluscum infection home from day care or school.

If you notice bumps on a child’s skin, it is reasonable to inform the child’s parents and to request a doctor’s note. Only a healthcare professional can diagnose molluscum contagiosum because there are many other causes of growths on the skin, both infectious and non-infectious.

Lesions not covered by clothing should be covered with a watertight bandage. Change the bandage daily or when obviously soiled.

If a child with lesions in the underwear/diaper area needs assistance going to the bathroom or needs diaper changes, then lesions in this area should be bandaged too if possible.

Covering the lesions will protect other children and adults from getting molluscum contagiosum and will also keep the child from touching and scratching the lesions, which could spread the infection to other parts of his/her body or cause secondary (bacterial) infections.

Children should be reminded to wash their hands frequently.

If day care or school employees with regular physical contact with others are normally required to have skin examinations during pre-employment physicals, then infection molluscum contagiosum should be noted.

Work

Although there has been only one reported case of healthcare provider-to-patient transmission of molluscum contagiosum, if an employee who comes in physical contact with clients regularly, such as an aesthetician or health care provider, is diagnosed with molluscum contagiosum by a health care professional, it would be reasonable to require that he/she cover visible lesions with a watertight dressing while at work. Otherwise, no special precautions are needed.

Other precautions can prevent or reduce spread to uninfected people:

• Frequent and correct hand hygiene practices. For handwashing tips and information, see the Clean Hands Saves Lives site.
• Requiring notation of molluscum contagiosum on examinations requested for—
  • Employment
    • Recommended only for employees with regular physical contact with clients (e.g., aestheticians, health care professionals, day care employees) who are normally required to have skin examinations during pre-employment physicals.
  • Camp
  • Sports physicals
• Recommending that all visible lesions be covered by a watertight dressing, if molluscum contagiosum is diagnosed by a healthcare professional during a physical examination.
• Routinely disinfecting shared equipment (e.g., kick boards, wrestling mats). The molluscum contagiosum virus is not particularly difficult to kill and usual sanitation procedures should be sufficient.

Other ways to avoid sharing your molluscum contagiosum infection

Do not shave or have electrolysis on areas with lesions.

Don’t share personal items such as unwashed clothes, hair brushes, wrist watches, and bar soap with others.

If you have lesions on or near the penis, vulva, vagina, or anus, avoid sexual activities until you see a health care provider.

Molluscum contagiosum signs and symptoms

Molluscum contagiosum presents as clusters of small round dome-shaped papules (bumps). The papules range in size from 1 to 10 mm and may be white, skin-colored, pink, pearly or brown and occur in clusters and sometimes in a straight line. They often have a waxy, shiny look with a small central pit (this appearance is sometimes described as umbilicated). Each papule contains white cheesy material.

There may be few or hundreds of papules on one individual. They mostly arise in warm moist places, such as the armpit, behind the knees, groin or genital areas. They can arise on the lips or rarely inside the mouth. They do not occur on palms or soles.

The bumps are usually painless and may occasionally itch. When molluscum contagiosum is autoinoculated by scratching, the papules often form a row. Individual bumps may get bigger over the course of 6–12 weeks. Usually the bumps do not grow larger than 10 mm, but in patients with weak immune systems, they can be larger than a nickel.

Molluscum contagiosum frequently induces dermatitis around them and affected skin becomes pink, dry and itchy. As the papules resolve, they may become inflamed, crusted or scabby for a week or two.

Molluscum contagiosum infections may be:

• Mild – under 10 lesions
• Moderate – about 10–50 lesions
• Severe – over 50 lesions

Common areas for molluscum contagiosum lesions are the chest, abdomen, back, armpits, groin, or backs of the knees. Occasionally, they can be seen on the face and genital region. Because the incubation period for molluscum contagiosum is 2 weeks to 6 months, lesions may not immediately be seen after contracting the virus. Molluscum contagiosum infection is self-limited, and lesions will go away on their own in 6–9 months, although they rarely can persist for a few years. As the bumps begin to resolve, they may initially appear more inflamed, with pus and crusting of the lesions, before they eventually fade. They usually do not leave a scar.

Molluscum contagiosum complications

Complications of Molluscum contagiosum can include:

• Secondary bacterial infection from scratching (impetigo)
• Conjunctivitis when the eyelid is infected
• Disseminated secondary eczema; this represents an immunological reaction or ‘id’ to the virus
• Numerous and widespread molluscum contagiosum that are larger than usual may occur in immune-deficient patients (such as uncontrolled HIV infection or in patients on immune
• suppressing drugs), and often affect the face
• Spontaneous, pitted scarring
• Scarring due to surgical treatment.

Molluscum contagiosum diagnosis

Your doctor will most likely be able to diagnose molluscum contagiosum by its appearance. Molluscum is usually recognized by its characteristic clinical appearance or on dermatoscopy. White molluscum bodies can often be expressed from the center of the papules.

Very rarely, a biopsy is required. Histopathology shows characteristic intracytoplasmic inclusion bodies.

Molluscum contagiosum treatment

Molluscum contagiosum viral skin infection will resolve on its own within a few months. Talk to your child’s doctor about whether he or she recommends treatment or watchful waiting. No treatment is 100% effective since scientists are currently unable to kill the virus, and most can have side effects such as pain or irritation of the skin.

Treatment for molluscum is usually recommended if lesions are in the genital area (on or near the penis, vulva, vagina, or anus) ⁶⁾. If lesions are found in this area it is a good idea to visit your healthcare provider as there is a possibility that you may have another disease spread by sexual contact.

• Be aware that some treatments available through the internet may not be effective and may even be harmful.

What are the treatment options for molluscum contagiosum ?

Because molluscum contagiosum is self-limited in healthy individuals, treatment may be unnecessary. Nonetheless, issues such as lesion visibility, underlying atopic disease, and the desire to prevent transmission may prompt therapy.

Possible treatments include the following:

• Cantharidin 0.7% or 0.9% liquid – This is an extract from the blister beetle. It is applied to the lesions and then washed off in 2–6 hours. It is not for use on the face or genitals.
• Removal with freezing (cryosurgery), scraping (curettage), or burning (electrocautery) – All of these options may be painful.
• Salicylic acid
• Podofilox (Condylox®)
• Tretinoin (Retin-A®)
• Trichloroacetic acid
• Silver nitrate paste
• Imiquimod cream (Aldara®) – This may be useful for widespread, difficult-to-treat lesions.

Physical removal

Physical removal of lesions may include cryotherapy (freezing the lesion with liquid nitrogen), curettage (the piercing of the core and scraping of caseous or cheesy material), and laser therapy. These options are rapid and require a trained health care provider, may require local anesthesia, and can result in post-procedural pain, irritation, and scarring.

• It is not a good idea to try and remove lesions or the fluid inside of lesions yourself. By removing lesions or lesion fluid by yourself you may unintentionally autoinoculate other parts of your body or risk spreading it to others. By scratching or scraping your skin you could cause a bacterial infection.

Oral therapy

Gradual removal of lesions may be achieved by oral therapy. This technique is often desirable for pediatric patients because it is generally less painful and may be performed by parents at home in a less threatening environment. Oral cimetidine has been used as an alternative treatment for small children who are either afraid of the pain associated with cryotherapy, curettage, and laser therapy or because the possibility of scarring is to be avoided. While cimetidine is safe, painless, and well tolerated, facial molluscum contagiosum do not respond as well as lesions elsewhere on the body.

Topical therapy

Podophyllotoxin cream (0.5%) is reliable as a home therapy for men but is not recommended for pregnant women because of presumed toxicity to the fetus. Each lesion must be treated individually as the therapeutic effect is localized. Other options for topical therapy include iodine and salicylic acid, potassium hydroxide, tretinoin, cantharidin (a blistering agent usually applied in an office setting), and imiquimod (T cell modifier). Imiquimod has not been proven effective for the treatment of molluscum contagiosum in children and is not recommended for children due to possible adverse events. These treatments must be prescribed by a health care professional.

Therapy for immunocompromised persons

Most therapies are effective in immunocompetent patients; however, patients with HIV/AIDS or other immunosuppressing conditions often do not respond to traditional treatments. In addition, these treatments are largely ineffective in achieving long-term control in HIV patients.

Low CD4 cell counts have been linked to widespread facial mollusca and therefore have become a marker for severe HIV disease. Thus far, therapies targeted at boosting the immune system have proven the most effective therapy for molluscum contagiosum in immunocompromised persons. In extreme cases, intralesional interferon has been used to treat facial lesions in these patients. However, the severe and unpleasant side effects of interferon, such as influenza-like symptoms, site tenderness, depression, and lethargy, make it a less-than-desirable treatment. Furthermore, interferon therapy proved most effective in otherwise healthy persons. Radiation therapy is also of little benefit.

What are the long-term effects of molluscum contagiosum ?

In immune competent hosts, molluscum contagiosum is a relatively harmless. The papules may persist for up to 2 years or longer. In children, about half of cases have cleared by 12 months, and two-thirds by 18 months, with or without treatment. Contact with another infected individual later on can lead to a new crop of mollusca.

Infection can be very persistent in the presence of significant immune deficiency.

Molluscum contagiosum doesn’t usually cause any long-term problems. The growths typically don’t leave any marks. Treatments might scar the skin, though, and some people develop an infection that needs to be treated with antibiotics.

Recovery from one molluscum infection does not prevent future infections. Molluscum contagiosum is not like herpes viruses which can remain dormant (“sleeping”) in your body for long periods of time and then reappear. If you get new molluscum contagiosum lesions after you are cured, it means you have come in contact with an infected person or object again.

Complications of molluscum contagiosum

The lesions caused by molluscum contagiosum are usually benign and resolve without scarring. However scratching at the lesion, or using scraping and scooping to remove the lesion, can cause scarring. For this reason, physically removing the lesion is not often recommended in otherwise healthy individuals.

The most common complication is a secondary infection caused by bacteria. Secondary infections may be a significant problem in immunocompromised patients, such as those with HIV/AIDS or those taking immunosuppressing drug therapies. In these cases, treatment to prevent further spread of the infection is recommended.