Molluscum contagiosum

Published on 19/03/2015 by admin

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Last modified 19/03/2015

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Molluscum contagiosum

Aysha Javed and Ian Coulson

Evidence Levels:  A Double-blind study  B Clinical trial ≥ 20 subjects  C Clinical trial < 20 subjects  D Series ≥ 5 subjects  E Anecdotal case reports

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Molluscum contagiosum (MC) is a common self-limiting poxvirus infection of the skin and occasionally mucous membranes. Lesions occur in children, usually on the trunk and body folds, and in young adults, if sexually transmitted, in the genital region. They typically present as multiple 1–10 mm diameter discrete, pearly white or flesh-colored umbilicated papules. They may be surrounded by an eczematous reaction, which disappears on resolution of the infection. Mollusca may be very extensive and recalcitrant to treatment in all forms of cell-mediated immunosuppression, especially in patients with AIDS.

Management strategy

There is no specific antiviral therapy for molluscum contagiosum. Physical and chemical destructive methods of treatment as well as topical and systemic immunostimulatory therapies have been tried, but no single intervention has been convincingly shown to be effective. Only a few have been subjected to the rigors of placebo-controlled studies, important for a condition that has a high spontaneous resolution rate.

The choice of therapy will depend on the age and immune status of the patient as well as the number and location of the lesions. In immunocompetent patients with few lesions it is reasonable to await spontaneous resolution, which will usually occur within a few months. Secondarily infected MC may need topical antiseptic or antibiotic treatment to minimize the risk of atrophic scarring. Active intervention may be justified for cosmetic reasons, or to hasten resolution, in order to prevent autoinoculation or transmission of the virus to close contacts. Avoidance of communal bathing and restriction of the sharing of towels should also help prevent the spread of infection to others.

A commonly used and inexpensive treatment is the manual extrusion of individual lesions using gloved fingers or fine forceps. This has proved more effective than cryotherapy applied every 3 to 4 weeks. Curettage and electrodesiccation of larger lesions may result in scarring and also requires pain alleviation, especially in children, by the prior application of a eutectic mixture of local anesthetics (lidocaine and prilocaine cream). Topically applied caustic agents have been used with variable results. Good success rates are reported with topical application of 40% silver nitrate paste, 0.5% podophyllotoxin, and 10% povidone-iodine with 50% salicylic acid. A useful alternative is 5% acidified nitrite, applied nightly with 5% salicylic acid under occlusion. Significant scarring has been documented with both potassium hydroxide and phenol, and the latter is no longer recommended. Although cantharidin has proved to be an effective treatment, it is not readily available in the UK and is not currently recommended by the Food and Drug Administration. The topical immune response modifier imiquimod has been shown to be effective and safe in several placebo-controlled studies. In patients with AIDS, both 1% imiquimod and topical cidofovir 3%, a competitive inhibitor of DNA polymerase, have proved successful for treating MC. Recovery of immune function with highly active antiretroviral therapy (HAART) may also result in the resolution of MC in these patients.

Second-line therapies

image Topical 5% acidified nitrite co-applied with 5% salicylic acid A
image Topical salicylic acid gel 12% A
image Topical 10% povidone-iodine and 50% salicylic acid B
image Topical 40% silver nitrate paste B
image Topical 0.5% podophyllotoxin B
image Cryotherapy C

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