Molluscum Contagiosum (MC)

Molluscum Contagiosum (MC) is a superficial skin infection that is caused by the molluscum contagiosum virus (MCV). This virus is similar to the one that causes small pox. It most commonly occurs in children and may occur in sexually active adults. MC is usually transmitted by direct skin to skin contact. It may also be transferred by indirect means, such as swimming in contaminated pools or a touching the surface where the virus might be found. A small abrasion in your skin may increase the likelihood of infection with MCV. The best way to prevent transmission of MCV is to avoid skin to skin contact with any individual known to have MC. The average interval between exposure to the virus and appearance of the rash is anywhere from 2 to 7 weeks and can be as long as 6 months.

Presentation:
MCV will colonize the epidermis (upper layer of the skin) and part of the hair follicle called the infindibulum. This results in the formation of many, round to oval papules or bumps ranging in size from 1-2 mm to lesions as large as 5-10 mm. The lesions of MC may be white, pearly or flesh-colored and have a central depression or dimple. They are not itchy or painful, except for some minor tenderness that occurs just before the rash is about to disappear. Gentle pressure applied to mollusca may cause some whitish material to be released. Lesions of MC will cluster in areas where skin touches skin such as the axilla (armpit), the groin or the space behind the knee. Clusters may also be found on the face, eyelids, chest, abdomen and buttocks. In sexually active adults, molluscum will be distributed in the groin, genital area, thighs and lower abdomen.

There are typically less than 30 lesions present at one time in a normal, healthy person. Patients with atopic dermatitis may have more widespread eruptions. Those with a compromised immune system, such as those with human immunodeficiency virus (HIV) also tend to have more widespread eruptions. They also have larger lesions (6-10mm) that are quite resistant to treatment. MC is usually diagnosed on the basis of clinical findings by your doctor. A biopsy of the lesion is rarely indicated unless the diagnosis is in question. MC may mimic other skin disorders such as warts and certain skin cancers; therefore, it is important to see your doctor for an accurate diagnosis.

Treatment:
MC is a self-limiting disease and lesions will spontaneously disappear after a period of inflammation and minor tenderness. The length of time an eruption lasts depends on the strength of your body’s immune system. In healthy individuals, MC will resolve spontaneously without scarring in anywhere from a few months to a few years. In individuals with a compromised immune system, spontaneous regression does not occur. Experts recommend treating MC to prevent spread by scratching, termed autoinoculation, or to prevent transmission to others.

Lesions may be eradicated by mechanical or chemical means. Some methods of mechanical destruction include cryosurgery (application of liquid nitrogen), evisceration (ejecting the core with a sharp object), curettage and tape-stripping. Some topical chemical agents include cantharidin, podophylin, tretinoin, and imiquimod. There have been case reports and some small studies that support the use of other agents such as potassium hydroxide, oral cimetidine, laser therapy and cidofovir; however, many of these treatments are still under investigation. Your doctor will help you decide which treatment is best for you.

References:
Hanson, D. & Diven, D.G.; Molluscum Contagiosum, Dermatology Online Journal; Volume 9 (2).
van der Wouden, JC et al; Interventions for Cutaneous Molluscum Contagiosum: The Cochrane Database of Systematic Reviews, 2007 (1)
Stulberg, D.L., MD & Hutchinson, A.G., MD; Molluscum Contagiosum and Warts; American Family Physician: March 15, 2003, Vol 67 (6)

Andrea Baratta, D.O.
Dermatology Department
St. John’s Episcopal Hospital South Shore
Far Rockaway, NY