Warts and molluscum are two common viral skin infections that produce bumps on the surface of the skin that can grow and spread. Most commonly these infections occur in young and school aged children but, based on a number of factors, can affect people of all ages. Luckily these infections tend to become less frequent with age for most and are usually easily treatable with early and consistent intervention for those patients more susceptible to infection.
Warts are a common skin infection. They are caused by the human papilloma virus (HPV) which gains entry to the skin through tiny breaks in the skin and lives in the outermost layer of the skin. Growth of the virus produces a bump with the characteristic rough, granular appearance. They are usually slightly lighter or darker than the color of the skin and sometimes have black dots in them which represent small clotted blood vessels at the base of the wart. Most often warts appear on the hands and feet but the virus can occur on any part of the body, including the face. Eventually, they may disappear on their own, although this can take years or even decades and lesions can grow or spread in the meantime. Moreover, they can be painful when they occur on the hands and feet and can be embarrassing when they occur on visible parts of the body.
Types of Warts
- Common wart - Common warts present as papules with a rough, papillomatous and hyperkeratotic surface ranging in size from 1 mm to larger than 1 cm. They arise most often on the backs of fingers or toes, around the nails—where they can distort nail growth—and on the knees. Sometimes they resemble a cauliflower; these are known as butcher’s warts.
- Plantar wart - Plantar warts (verrucas) include tender inwardly growing and painful ‘myrmecia’ on the sole, and clusters of less painful mosaic warts. Plantar epidermoid cysts are associated with warts. Persistent plantar warts may rarely be complicated by the development of verrucous carcinomas.
- Plane wart - Plane warts have a flat surface. The most common sites are the face, hands and shins. They are often numerous. They may be spread by shaving or scratching so that they appear in a linear distribution (pseudo-Koebner response). Plane warts are mostly caused by HPV types 3 and 10.
- Filiform wart - Filiform warts are on a long stalk like a thread. They commonly appear on the face. They are also described as digitate (like a finger).
- Genital warts - occur in the genital area and on the sexual organs. The are considered to be a sexually transmitted disease. This is the only type of wart considered to be a serious health issue because the HPV virus can develop into cervical cancer in women and (less commonly) into penile cancer in men. The HPV virus is responsible for at least 95 percent of cervical cancers and the virus can also be transmitted to a newborn during birth.
- Mucosal wart - Oral warts can affect the lips and even inside the cheeks, where they may be called squamous cell papilomas. They are softer than cutaneous warts.
- Over the Counter Treatments - it is important to seek the advice of a dermatologist before using OTC wart treatments if you are unsure of the diagnosis. When deciding to try the self-care approach with warts, there are several products available on the market. The most effective products have the active ingredient salicylic acid, which works by drying out the wart and sloughing off the skin protecting the infection site. It is important to treat only the wart, since these products can irritate surrounding skin. While effective, these options require persistence and can take months of daily treatment to completely resolve the infection.
- Freezing (cryotherapy) - this method can destroy a wart by freezing it with liquid nitrogen. As the skin thaws, the dead skin (the wart) falls off. This method is effective but can sometimes require multiple treatments.
- Electrodesiccation and curettage—this treatment involves cutting away the wart or destroying the wart by using electric cautery.
- HPV vaccines - Two HPV vaccines are licensed by the FDA and recommended by CDC for boys and girls as early as 11-12 yearsof age. These vaccines are Cervarix (made by GlaxoSmithKline) and Gardasil (made by Merck).
- Injections - injections such as the anti-cancer drugs bleomycin or fluorouracil can be injected directly into the wart to kill the virus at its base.
Molluscum contagiosum, also known as molluscum or simply MC, is a viral infection of the skin caused by a poxvirus that mainly affects infants and young children under the age of 10 but can sometimes affect adolescents and adults. The result of the infection is usually a benign, mild skin disease characterized by growths that may appear anywhere on the body. Within 6-12 months, Molluscum contagiosum typically resolves without scarring but in some cases may take as long as 4 years to resolve without medical intervention.
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 and are 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 can become itchy, sore, red, and/or swollen.
Mollusca may develop alone or in groups anywhere on the body including the face, neck, arms, legs, and abdomen but often favor warm moist places, such as the armpit, behind the knees, groin or genital areas. Unlike warts, these lesions are rarely found on the palms of the hands or the soles of the feet.
How Does Molluscum Spread?
As its name implies, to those susceptible to infection, molluscum contagiosum is very contagious. The virus that causes molluscum spreads from direct person-to-person physical contact and through contaminated items that can include linens such as clothing and towels, bathing sponges, pool equipment, and toys. Transmission is more likely in warm, wet, and overcrowded environments such as shared baths and pools.
Once infected, someone with molluscum can spread it to other parts of their body by touching or scratching a lesion and then touching their body somewhere else in a process known as autoinoculation. Other routine abrasive activities such as shaving or exfoliating can also result in the development of additional mollusca.
Molluscum can also spread from one person to another through sexual contact. Many, but not all, cases of molluscum in adults are caused by sexual transmission.
Molluscum contagiosum tends to be more numerous and last longer in children who also have eczema, due to deficiencies in the skin barrier which allow the virus to enter the surface of the skin more easily. It can be very extensive and troublesome in patients with human immunodeficiency virus (HIV) infection or that have other reasons for poor immune function.
Because molluscum contagiosum is self-limited in healthy individuals, treatment may be unnecessary. Nonetheless, issues such as lesion visibility, underlying atopic disease, secondary infection, and the desire to prevent transmission may prompt therapy. Treatment for molluscum is usually recommended if lesions are in the genital area. If lesions are found here 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.
A range of treatment options are available but efficacy and tolerance vary for each individual patient so it is important to consult with a healthcare provider to determine which treatment plan is the best fit. Common treatment methods include:
- Cantharidin - This in office treatment involves the application of a topical medication to each individual lesion. The application process is painless but the medication must be washed off in 1-2 hours at home and the patient must avoid touching the treated areas until then. Within a day, blisters form at the sites of application which can cause some discomfort for a few days after treatment so this option is not recommnded for sensitive areas. This process provokes an immune response in the area to combat the infection and the blister lifts the infected skin away from the surrounding normal skin to stop the spread of the virus.
- Extirpation - Utilizing a small sterile blade, this office treatment involves scratching the surface of each lesion to provoke an immune response in that area of the skin to attack the virus. While more effective than cantharidin application, there is mild discomfort associated with the process which can be intolerable for some children but there is no discomfort following the procedure unlike cantharidin therapy.
- Cryotherapy - Like with wart treatment, this method involves spraying each lesion with liquid nitrogen to freeze infected skin cells, killing off the virus at the treatment site. This is the most effective office therapy but also involves the most discomfort during the treatment and, if blisters form in treated areas, can cause discomfort for a few days following each treatment. Because of this, it is most often used for adolescent and adult patients.
- Podophyllotoxin - Originally derived from the roots of the North American mayapple tree, this topical prescription treatment can be used to treat molluscum lesions at home. While less effective than office based treatments, this is an alternative for pediatric patients with few lesions or that find other treatment methods intolerable and prefer the comfort of treatment in the home. Parents and patients must be committed to diligent daily application of the medication every day for weeks or months to acheive desired results.
- Cimetidine - Another at-home therapy sometime used in combination with topical podophyllotoxin, this oral presecription medication can be used to treat molluscum infections. This method is also popular with pediatric patients who would prefer the comfort of treatment outside the office environment. While cimetidine is safe and painless, it does have a bitter taste which many children have difficulty tolerating on its own and sometimes even when mixed with food items.
Regardless of treatment method, the most important factor to success in treatment is consistency. Remember to be persistent and keep all scheduled follow ups until the infection is completely resolved as gaps in treatment can allow the molluscum infection to spread, nullifying any progress gained from previous treatments.