Molluscum Contagiosum Treatment & Management

In healthy patients, molluscum contagiosum is generally self-limited and heals spontaneously after several months. Individual lesions are seldom present for more than 2 months. Although treatment is not required, it may help to reduce autoinoculation or transmission to close contacts and improve clinical appearance.

Intervention may also be indicated if lesions persist. Therapeutic modalities include topical application of various medications, radiation therapy, and/or surgery. Each technique may result in scarring or postinflammatory pigmentary changes. Frequently, multiple treatment sessions are necessary because of the recurrence of treated lesions and/or the appearance of new lesions by autoinoculation. The benefit of therapy must exceed the risk.

Therapeutic options for molluscum contagiosum can be divided into broad categories, including the following:

• Benign neglect
• Direct lesional trauma
• Antiviral therapy
• Immune response stimulation

Choice of therapy

The most appropriate therapeutic approach largely depends on the clinical situation. In healthy children, a major goal is to limit discomfort, and benign neglect or minor, direct lesional trauma is appropriate. In adults who are more motivated to have their lesions treated, cryotherapy or curettage of individual lesions is effective and well tolerated.

In immunocompromised individuals, molluscum contagiosum may be very extensive and difficult to treat. The goal may be to treat the most troublesome lesions only. In severe cases, these patients may warrant more aggressive therapy with lasers, imiquimod, antiviral therapy, or a combination of these. Of course, effective antiretroviral therapy in patients with AIDS makes therapy of molluscum contagiosum much more effective.

The US Food and Drug Administration (FDA) has approved none of the topical or intralesional agents for treatment of molluscum contagiosum.

In a study of the treatment of molluscum contagiosum in children, Hanna et al determined that curettage was the most efficacious therapy. The investigators conducted a prospective, randomized trial that compared the efficacy and adverse effects of 4 recognized treatments of molluscum contagiosum in 124 children.^[25] One group was treated with curettage, a second with cantharidin, a third with a combination of salicylic acid and lactic acid, and a fourth with imiquimod.

Curettage was found to be the most efficacious treatment and had the lowest rate of side effects. However, it must be performed with adequate anesthesia and is a time-consuming procedure. Cantharidin had moderate complications due to blisters and was slightly less effective. The topical keratolytic used was too irritating for children. Topical imiquimod was more effective than cantharidin but is expensive, and an optimum treatment schedule has yet to be reported.

Follow-up

Repeat examination is recommended 2-4 weeks after treatment. Retreatment often is necessary. Consider combination therapy in patients whose lesions respond poorly.

Activity

Instruct the patient to avoid activities or sports involving physical contact between infected areas of skin and exposed skin of other participants.

Deterrence and prevention

Most cases in adolescents and adults are secondary to sexual contact. Abstinence and careful selection of sexual partners are important. Whether condoms are effective in preventing spread is unclear. Good personal hygiene is important in limiting transmission. Autoinoculation may result from trauma, such as shaving or the manipulation of lesions by the patient.

Clinical success has been reported with the use of the following topical agents, which may act as irritants, stimulating an immunologic response:

• Imiquimod cream - An immune response modifier approved for the treatment of external genital and perianal warts in adults, imiquimod cream has been reported to be effective in the treatment of molluscum contagiosum^{[26, 27]} ; imiquimod cream may be used in conjunction with cantharidin^[28]
• Cantharidin - Several studies report that cantharidin, a chemovesicant that can be used in combination with imiquimod, is effective in treating molluscum contagiosum; to test the patient's response to therapy, treat only a few lesions on the initial visit^[28]
• Tretinoin - This agent has reportedly been successful in the treatment of small molluscum contagiosum lesions
• Bichloracetic acid
• Trichloroacetic acid
• Salicylic acid
• Lactic acid
• Glycolic acid
• Silver nitrate

Tretinoin, cantharidin, and imiquimod may be dispensed to the patient with application instructions and close follow-up, although some recommend application in the office. Bichloracetic acid, trichloroacetic acid, salicylic acid, lactic acid, glycolic acid, and silver nitrate must be applied in the office by the physician.

Topical podophyllotoxin 0.5% cream self-administered twice daily for 3 weeks has been reported effective in a placebo-controlled, double-blind study.^[29]

Reports have suggested that subcutaneous interferon alfa administered intralesionally may be useful in immunocompromised children.

A case report noted the efficacy of topical cidofovir in the treatment of disseminated molluscum in immunodepressed patients.^[6] Cidofovir diphosphate was reported to inhibit molluscum contagiosum virus DNA polymerase activity.^[30]

Leaving mollusca to spontaneously resolve is often reasonable,^[31] especially in young children for whom freezing or curettage may be painful and frightening. The dictum primum non nocere (first do no harm) has a special significance in children with minor, self-limited conditions. Many physicians refuse to treat children with small numbers of mollusca.

Lesions on the eyelids and central face may be particularly distressing to parents and patients. When possible, treat lesions at other locations first, with the hope that the treatment may stimulate the facial lesions to spontaneously resolve. When facial lesions require treatment, the best option is to treat them frequently with minor physical trauma. (See the image below.)

More aggressive therapy may be required in patients in whom the extent of disease is intolerable and in patients who are immunocompromised.

Takematsu et al reported that disruption of the epidermal wall of Henderson-Paterson bodies induces acute inflammatory changes by activation of the alternative complement pathway on exposure to the tissue fluids; furthermore, the Henderson-Paterson bodies release proinflammatory cytokines and other neutrophil chemotactic factors upon decomposition.^[32] This supports the observation that minor trauma to molluscum lesions frequently produces an inflammatory response and resolution of the lesion. The Henderson-Paterson bodies can be ruptured and a local inflammatory response created by various forms of physical trauma and caustic topical agents.

Various caustic agents have been shown to be effective in treating molluscum contagiosum. Tretinoin, salicylic acid, and potassium hydroxide^{[33, 34]} may be used. Cantharidin,^{[28, 35]} silver nitrate,^[36] trichloroacetic acid, and phenol also are options. Children may tolerate therapy with these agents better than curettage or cryotherapy. None of these caustic agents has been approved by the FDA for treatment of molluscum contagiosum.

Tretinoin cream

Tretinoin cream 0.1% or gel 0.025% is applied daily. Apply it to a region of skin with scattered lesions. It may produce eczema and may increase the number of lesions through autoinoculation; however, a small amount of tretinoin may be applied to individual lesions with the rough end of a broken toothpick. Rotate the toothpick, gently abrading the lesion and increasing the inflammatory response produced by the tretinoin. Treat lesions every few days until significant inflammation or resolution occurs.

Potassium hydroxide

Potassium hydroxide is a strong alkali that has long been known to digest proteins, lipids, and most other epithelial debris of skin scrapings to identify fungal infections. Topical 10% potassium hydroxide aqueous solution applied twice daily on each molluscum contagiosum lesion until all lesions undergo inflammation and superficial ulceration may be effective in clearing molluscum contagiosum in children.

Cantharidin

Cantharidin is a chemovesicant that is highly effective in treating molluscum contagiosum; however, this agent has lost favor with some physicians because of concerns regarding its safety. However, if cantharidin is used properly, it is very effective, safe, and well tolerated by children.

In a study by Silverberg et al in which 300 patients were treated with cantharidin, 90% of patients experienced complete clearing after an average of 2.1 visits. Blisters occurred at sites of application in 92% of patients. Temporary burning, pain, erythema, or pruritus was reported in 6-37% of patients. No major adverse effects were reported, and no patients experienced secondary bacterial infection. A total of 95% of parents reported that they would proceed with cantharidin therapy again.^[37]

Cantharidin is not approved by the FDA for treatment of any condition; however, it has been used safely and effectively by dermatologists for many years.^{[38, 39]} It is listed as acceptable therapy in the American Academy of Dermatology treatment guidelines for warts; however, because it has never been approved by the FDA for use in humans, it is no longer marketed as medical therapy in the United States. Cantharidin crystals and diluent can be purchased in the United States, and many dermatologists continue to use it. Cantharidin solution for the treatment of warts and molluscum is available in Canada and many other countries.

Salicylic acid

Seventeen percent salicylic acid in collodion (Compound W, Freezone, Wart-Off, Occlusal) is commonly used in treating verruca vulgaris. In most patients, repeated application to individual molluscum contagiosum lesions until an inflammatory response is generated is effective therapy.

Physical trauma

Varying degrees of physical trauma to individual lesions are used and are frequently quite successful. Physical trauma to individual molluscum contagiosum lesions can be performed with cryotherapy, lasers, curettage,^{[40, 41]} expression of the central core with tweezers, rupture of the central core with a needle or a toothpick,^{[42, 43]} electrodesiccation, shave removal, or duct tape occlusion.^[44]

Instruct the parents to tease out the firm, white core at the center of lesions using a clean needle or a toothpick. The process of irritating the lesion usually causes it to inflame and resolve within 1-2 weeks. This safe and easy approach can be performed by the patient's parent, limiting the need for follow-up visits.

In an office setting, curettage of individual lesions is easy and very effective. With a sharp curette and a quick firm motion, small, individual lesions can be removed completely, with little or no bleeding. With practice and a sharp curette, the provider may perform this procedure with little or no discomfort. Older children, adolescents, and adults usually tolerate this procedure better.

Other simple mechanical methods, such as expression of the contents in the papule by squeezing it with forceps held parallel to the skin surface or shaving off the lesions with a sharp scalpel, are effective.

Lesions may also be treated with light electrodesiccation. At very low voltage settings, anesthesia may not be required.

Cryotherapy is the first-line treatment for many physicians, particularly in adolescents and adults. A brief freeze, which causes icing of the lesion and a thin rim of surrounding skin, is usually adequate. Treatment is repeated at intervals of 2-3 weeks until all lesions resolve. Achieve accurate spray of liquid nitrogen by using a disposable ear speculum. The small end is placed against the skin, and liquid nitrogen is sprayed into the funnel created. Lesions also may be treated with cotton-tip applicators chilled in liquid nitrogen and held against the lesion until a small amount of frosting occurs. Cryotherapy is painful and the smoke that rises off the cold applicator or the noise of the liquid nitrogen sprayer may be quite frightening to younger children.

Pulsed dye laser (PDL) therapy has been shown to be more than 95% successful in treating individual lesions with 1 treatment. PDL treatment of molluscum contagiosum has been used successfully in patients with AIDS. A significant reduction in the number of molluscum contagiosum lesions following a single treatment with the PDL can be attained. Treated areas may remain disease-free for months. Although cost and availability are major limiting factors for routine use, PDL therapy may be considered for treatment of extensive or resistant lesions. It may also be valuable in immunocompromised individuals with extensive disease.^{[45, 46, 47, 48, 49]}

Treatment of molluscum contagiosum in patients with AIDS remains a challenge. The combination of 2 or more therapeutic modalities, such as carbon dioxide laser, PDL, and trichloroacetic acid, can be of much help to improve the quality of life of these patients.

The discomfort of curettage or other mechanical removal may be reduced. Lesions may be sprayed with ethyl chloride until frosting has occurred and then scraped away with a curette. The application of local anesthetic cream, EMLA (a eutectic mixture of 5% lignocaine and prilocaine) or its equivalent, may permit painless treatment. The cream is best applied under occlusion 1-2 hours before the planned procedure.

Imiquimod cream, intralesional interferon alfa,^[50] and topical injections of streptococcal antigen^[51] have been shown to be effective in treating patients with resistant molluscum contagiosum. The high cost of these products limits their use to more extensive or resistant infections. Imiquimod cream applied 3 times per week for 16 weeks is an option in severe cases. The dosing schedule and length of treatment require further evaluation.^{[25, 27, 52, 53, 54, 55, 56, 57]}

Imiquimod is a novel topical immune response modifier that is a potent inducer of interferons. Various treatment regimens have been effective in treating molluscum contagiosum. In children^{[58, 59]} and in some patients with AIDS-associated molluscum contagiosum,^{[60, 26]} 1% cream applied 3 times daily or 5% cream applied at every bedtime for 4 weeks appears to be effective treatment.

A newer compound, Veregen,is a sinecatechin. Its true mechanism of action is unknown. It is a botanical extract from green tea. The 15% ointment is applied topically 3 times a day. It is FDA approved for topical therapy for external genital warts and perianal warts, but it is used off label for molluscum as well as verruca plana.^[61]

In immunocompromised patients, improvement of lesions has been observed in individual patients treated with ritonavir, cidofovir (intravenous and topical),^{[62, 63]} and zidovudine. Not surprisingly, patients with AIDS and severe molluscum contagiosum improve with effective antiretroviral therapy.