Molluscum contagiosum is characterized by clusters of pink, dome-shaped, smooth, waxy, or pearly and umbilicated papules 2 to 5 mm in diameter caused by molluscum contagiosum virus, a poxvirus. Diagnosis is based on clinical appearance. Treatment aims to prevent spread or remove cosmetically unacceptable lesions and can include mechanical methods (eg, curettage, cryosurgery) and topical irritants (eg, imiquimod, cantharidin, tretinoin).
Molluscum contagiosum virus commonly causes a localized chronic infection. Transmission is by direct contact; spread occurs by autoinoculation and via fomites (eg, towels, bath sponges) and bath water. Molluscum contagiosum is common among children. Adults acquire the infection via close skin-to-skin contact with an infected person (eg, sexual contact, wrestling). Patients with immunocompromise (eg, due to HIV/AIDS, corticosteroid use, or chemotherapy) may develop a more widespread infection.
Molluscum contagiosum can appear anywhere on the skin except the palms and soles. Lesions consist of clusters of pink, dome-shaped, smooth, waxy, or pearly and umbilicated papules, usually 2 to 5 mm in diameter, which occur most commonly on the face, trunk, and extremities in children and on the pubis, penis, or vulva in adults. Lesions may grow to 10 to 15 mm in diameter, especially among patients with HIV infection and other immunodeficiencies.
Lesions are usually not pruritic or painful and may be discovered only coincidentally during a physical examination. However, the lesions can become inflamed and itchy as the body fights off the virus.
Diagnosis of molluscum contagiosum is based on clinical appearance; skin biopsy or smear of expressed material shows characteristic inclusion bodies but is necessary only when diagnosis is uncertain.
Most lesions spontaneously regress in 1 to 2 yr, but they can remain for 2 to 3 yr. Treatment of molluscum contagiosum is indicated for cosmetic reasons or for prevention of spread. Options include curettage, cryosurgery, laser therapy, electrocautery, trichloroacetic acid (25 to 40% solution), cantharidin, podophyllotoxin (in adults), tretinoin, and tazarotene. Some clinicians use salicylic acid, but others consider it too irritating for many body areas where molluscum occurs. Similar concerns exist with use of potassium hydroxide (KOH). Imiquimod is usually not recommended (1). Molluscum lesions within the orbital rim should be removed via gentle destruction by a skilled health care practitioner. Lesions may be gently squeezed with a forceps to remove the central core. Treatments that cause minimal pain (eg, tretinoin, tazarotene, cantharidin) are used first, especially in children.
Curettage or liquid nitrogen can be used 40 to 60 min after application of a topical anesthetic such as eutectic mixture of local anesthetics (EMLA) or 4% lidocaine cream under an occlusive dressing. EMLA cream must be applied judiciously because it can cause systemic toxicity, especially in children. In adults, curettage is very effective but painful if done without anesthetic. Dermatologists often use combination therapy such as liquid nitrogen or cantharidin in the office or a retinoid cream at home. This form of therapy is typically successful, but resolution often takes 1 to 2 mo in some patients.
Cantharidin is safe and effective but can cause blistering. Cantharidin is applied in 1 small drop directly to the molluscum lesion. Areas that patients (especially children) may rub are covered with a bandage because contact with the fingers should be avoided. Cantharidin should not be applied to the face or near the eyes because blistering is unpredictable. If cantharidin comes into contact with the cornea, it can cause scarring. Cantharidin should be washed off with soap and water in 6 h. Fewer than 15 lesions should be treated in one session because infection may occur after application of cantharidin. Parents should be warned about blistering if their children are prescribed this drug.
Children should not be excluded from school or day care. However, their lesions should be covered to reduce the risk of spread.
Molluscum contagiosum, caused by a poxvirus, commonly spreads by direct contact (eg, sexual contact, wrestling), fomites, and bath water.
Lesions tend to be asymptomatic clusters of 2- to 5-mm diameter papules that are pink, dome-shaped, smooth, waxy, or pearly and umbilicated.
Diagnosis is based on clinical appearance.
Treatment is for cosmetic reasons or prevention of spread.
Treatments can include destructive methods (eg, curettage, cryosurgery, laser therapy, electrocautery) or topical irritants (eg, trichloroacetic acid, cantharidin, tretinoin, tazarotene, podophyllotoxin).
Drug NameSelect Trade
cantharidinNo US brand name