Molluscum contagiosum is a very common viral skin condition in children. “Molluscum” are small dome-shaped bumps on the skin that have a central white or “waxy” core. They can affect any area of skin, but are prone to spread in areas of friction, such as the armpits and the creases at the elbows and behind the knees. Although individual susceptibility varies, children with chronic skin conditions, such as eczema, are somewhat more likely to develop molluscum. Molluscum are potentially contagious and are spread through physical contact. For siblings and close contacts, high risk activities include bathing together and sleeping in the same bed. Molluscum are generally not harmful, but they can become irritated or inflamed and sometimes cause an itchy rash on the surrounding skin. Without treatment, molluscum usually resolve spontaneously within a few months, although occasionally they may last up to two to three years.
While there is no single guaranteed cure for molluscum, there are a variety of treatments that may be helpful. These typically fall into two broad categories: those aimed at physical destruction of the lesions and those aimed at stimulating an immune response against the virus causing the lesions. Some methods employed to destroy the lesions directly include physical removal of the central viral core or freezing the lesions with liquid nitrogen. Of course, these methods are less desirable because they are painful and carry a higher risk of scarring.
An alternative and less traumatic method of physical destruction is the application of a liquid known as cantharidin. Originally isolated from a blister beetle (and also known as “blister beetle juice”), cantharidin is applied sparingly to the lesions in the office setting. Instructions are given to wash the treated areas well with soap and water within a few hours, depending on the concentration of cantharidin used. Within 24-48 hours, a superficial blister should appear at the site of application. The blisters are not usually painful and should dry up and fall off within 1-2 weeks. Cantharidin is not appropriate for use on the face, genitalia, or between the buttocks. I do not recommend covering treated areas with bandages or tape as this can cause larger areas of blistering. I also do not recommend treating more than about 20-30 lesions at once, so some children may require multiple treatments.
For some situations, such as more sensitive locations (e.g., face, groin), it is more appropriate to use a prescription cream aimed at stimulating an immune response against the viral infection. Imiquimod cream (Aldara™) is FDA approved to treat genital warts in patients age 12 and older, but is used frequently as an “off-label” treatment for molluscum. A small amount of the cream is applied to the affected areas at bedtime a few nights a week. The main side effect of this cream is local irritation of the skin. In addition, it may take 2-3 months or longer to see results. Another cream that is used “off-label” to treat molluscum in children is tretinoin. Tretinoin comes in a variety of preparations that are commonly used to treat acne. Like imiquimod, it is applied sparingly to lesions at bedtime several nights per week as tolerated. It can also be irritating to normal skin and may take several weeks to months to result in improvement.
Although molluscum can certainly be uncomfortable and unattractive, they do not usually cause serious problems in otherwise healthy children. It is important to keep in mind that treatments are not always rapidly curative and that the lesions nearly always resolve spontaneously over time.