Approach Considerations
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.
Therapeutic options for molluscum contagiosum can be divided into broad categories, including the following:
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Benign neglect
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Direct lesional trauma
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Antiviral therapy
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Immune response stimulation
European guidelines exist for the treatment of genital molluscum. [27]
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, antiviral therapy, or a combination of these. [28] 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 four previously recognized treatments for molluscum contagiosum in 124 children. [29] 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 adverse effects. However, it must be performed with adequate anesthesia and is a time-consuming procedure. Cantharidin is generally well tolerated, but this study had moderate complications owing to blisters and was slightly less effective. The topical keratolytic used was too irritating for children. Topical imiquimod has been found to be ineffective in several studies, and combination therapy may be required. [30, 31, 32, 33, 34, 35]
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.
Pharmacologic Therapy
Clinical success has been reported with the use of the following topical agents, which may act as irritants, stimulating an immunologic response:
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Cantharidin: Several studies report that cantharidin, a chemovesicant that has been 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. [36]
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Tretinoin - This agent has reportedly been successful in the treatment of small molluscum contagiosum lesions
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Bichloracetic acid
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Trichloroacetic acid
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Salicylic acid
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Lactic acid
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Glycolic acid
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Silver nitrate
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Potassium hydroxide
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Dilute povidone iodine
Tretinoin and cantharidin 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, potassium hydroxide, and silver nitrate must be applied in the office by the physician. [37]
Topical podophyllotoxin 0.5% cream self-administered twice daily for 3 weeks has been reported effective in a placebo-controlled, double-blind study. [38] Dilute povidone iodine has also been used. [39]
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. [5] Cidofovir diphosphate was reported to inhibit molluscum contagiosum virus DNA polymerase activity. [40]
Imiquimod cream is an immune response modifier approved for the treatment of external genital and perianal warts in adults. In the past, it was used in molluscum contagiosum; however, imiquimod cream has been reported to be ineffective in the treatment of molluscum contagiosum, [30, 31, 32, 33] particularly in children, in whom adverse effects have been noted. [32]
Benign Neglect
Leaving mollusca to spontaneously resolve is often reasonable, [41] 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.
Direct Lesional Trauma
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. [42] 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 [43, 44] may be used. Cantharidin, [36, 45] silver nitrate, [46] 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. [47]
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. [48, 49] 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, [50, 51] expression of the central core with tweezers, rupture of the central core with a needle or a toothpick, [52, 53] electrodesiccation, shave removal, or duct tape occlusion. [54]
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. [55, 56, 57, 58, 59]
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.
Immune Response Stimulation
Intralesional interferon-alfa [60] and topical injections of streptococcal antigen [61] 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. The dosing schedule and length of treatment require further evaluation.
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. [62]
Antiviral Therapy
In immunocompromised patients, improvement of lesions has been observed in individual patients treated with ritonavir, cidofovir (intravenous and topical), [63, 64] and zidovudine. Not surprisingly, patients with AIDS and severe molluscum contagiosum improve with effective antiretroviral therapy.
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Note the central umbilication in these classic lesions of molluscum contagiosum.
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Molluscum contagiosum. Approximately 10% of patients develop eczema around lesions. Eczema associated with molluscum lesions spontaneously subsides following removal.
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Molluscum contagiosum on the shaft of the penis. Molluscum contagiosum in the genital region of adults is most commonly acquired as a sexually transmitted disease.
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Molluscum contagiosum. Larger lesions may have several clumps of molluscum bodies rather than the more common single central umbilication. This may make them difficult to recognize as molluscum contagiosum.
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Molluscum lesions may become quite numerous in intertriginous areas. This child has autoinoculated lesions to both inner thighs.
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After trauma, or spontaneously after several months, inflammatory changes result in suppuration, crusting and eventual resolution of the lesion. This inflammatory stage does not usually represent secondary infection and seldom requires antibiotic therapy.
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Lesions of molluscum contagiosum have a characteristic histopathology. Lobules containing hyalinized molluscum bodies, also known as Henderson-Paterson bodies, are diagnostic.
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This lesion of cutaneous coccidioidomycosis could be included among the differential diagnoses of molluscum contagiosum.
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This keratoacanthoma could be included among the differential diagnoses of molluscum contagiosum.
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Molluscum contagiosum. Lesions on the upper eyelid of a 3-year-old child.
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In a patient who had preexisting molluscum contagiosum, the virus was inoculated along a line of minor skin trauma, resulting in the development of the 3 new lesions.
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Molluscum contagiosum on the right axilla.
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Presented here are the classic umbilicated papules of molluscum contagiosum lesions on the cheek of a child. Facial lesions occur frequently in children, although lesions generally are few.
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Molluscum contagiosum rarely occurs on the face in an adult unless the patient is infected with HIV. When molluscum contagiosum occurs in individuals infected with HIV, facial lesions are common and frequently numerous.
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Molluscum contagiosum lesions in individuals infected with HIV may number in the hundreds. In addition, they may become quite large and prominent.
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This low-power view of a molluscum contagiosum lesion shows the classic cup-shaped invagination of the epidermis into dermis. The Henderson-Paterson bodies are identified readily and stained purple to red in this image.
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This is a medium-power view of a molluscum contagiosum lesion. Magnification allows better demonstration of the intracytoplasmic molluscum bodies (staining purple-pink) within the keratinocytes.
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This molluscum contagiosum body is an intracytoplasmic inclusion body. Notice in the image that the keratinocyte nuclei are displaced to the periphery of the cell and that the intracytoplasmic inclusions have a granular quality.
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Multiple papules on the face of a man with HIV.
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Cytoplasmic viral inclusions become progressively larger toward the epidermal surface (hematoxylin and eosin, 200X)
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Low-power histopathologic examination reveals an overall cup-shaped appearance.
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Viral particles have a dumbbell-shaped appearance. Courtesy of Alvin Zelickson, MD.
