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An open label safety study of topical imiquimod 5% cream in the treatment of molluscum contagiosum in children

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An open label safety study of topical imiquimod 5% cream in the treatment of molluscum contagiosum in children
Alicia R. Barba MD, Sonia Kapoor MD and Brian Berman MD PhD
Dermatology Online Journal 7 (1):20

University of Miami Department of Dermatology and Cutaneous Surgery, Miami, FL.


The objective of this study was to evaluate the safety of imiquimod 5% cream, a potent inducer of interferons, in children with molluscum contagiosum. The lesions of thirteen subjects (mean age 7 years) were treated every night for 4 weeks. A visual analog scale was used to assess any adverse local skin reactions, and for the presence of systemic side effects characteristic of interferon (IFN). Temperature and total white blood cell count were measured at baseline and compared with results at weeks 2 and 4. In the twelve subjects who completed the study, adverse reactions were limited to application site reactions. We did not find any evidence of systemic toxicity. In conclusion, imiquimod 5% cream appears to be a safe treatment in children with molluscum contagiosum.


Molluscum contagiosum (MC) is a benign viral infection of the skin, caused by a DNA poxvirus, of which there are three types (MCV I, MCV II, MCV III). Molluscum contagiosum affects mostly children and young adults, and the infection is commonly transmitted through contact with an infected person, autoinoculation or contact with fomites [1]. Complete resolution of lesions can take up to 6-8 months, often requiring physical destruction of the lesions not only for cosmetic purposes but to prevent autoinoculation and infection of others [2]. Conventional treatments for MC includes cryotherapy, curettage, and topical application of caustic agents such as cantharidin, silver nitrate, or trichloracetic acid, treatments that are often painful and not feasible for widespread lesions.

Topical imiquimod (Aldara) 5% cream has been successfully used for the treatment of chronic giant molluscum contagiosum in one patient with human immunodeficiency virus disease and recalcitrant MC [3]. Subcutaneous interferon (IFN)-alpha treatment for widespread MC infection has also been reported [4]. Imiquimod is an immune response modifier capable of inducing high levels of interferon (IFN)-alpha, a potent antiviral agent, localized to the site of skin application [5]. Although no systemic effects of IFN-alpha were noted in adults receiving topical imiquimod as a 5% cream for the treatment of condyloma acuminata [6], this pilot study was undertaken to determine the safety of topical application of imiquimod 5% cream to the affected skin of children with molluscum contagiosum.

Materials and Methods

Thirteen healthy children ranging from 4 and 10 years of age (mean 7) with a clinical diagnosis of MC participated in this study approved by the University of Miami Institutional Review Board for children 3 to 18 years of age. One parent of each subject signed an informed consent form. Patients with a history of allergy to imiquimod, HIV infection, organ transplant, cardiac disease or depression were excluded from the study. Exclusion criteria also included pregnancy and age less than 3 years.

Parents were instructed to apply imiquimod 5% cream (Aldara, 3M Pharmaceuticals St. Paul, MN) on each lesion with a cotton tipped applicator before bedtime, and to wash the area(s) in the morning. Parents were asked to return all used and unused sachets with each follow-up visit. Patients were evaluated at baseline, week 2 and week 4 and assessments included a skin exam and medical history, including a history of atopy. Adverse local skin reactions were defined as pruritus, erythema, burning, erosion, and tenderness. Symptoms were evaluated and scored by utilizing a 10-point visual analog scale, filled out by the parent or when appropriate, the child, where 0 = none, 0.1-2.5 = nominal, 2.6-5.0 = mild, 5.1-7.5 = moderate, 7.6-10.0 = severe. Subjects were questioned regarding the presence of side effects characteristic of systemic IFN; fever, chills, headache, and myalgias. In addition, the temperature and total white blood cell count were measured at baseline and compared with follow up visits at weeks 2 and 4. A target lesion was chosen at baseline and a secondary end point, efficacy, was assessed by monitoring for resolution of this baseline target lesion at the end of 4 weeks.


Parents readily accepted a topical cream as an alternative possible therapy for MC. Of the 13 patients enrolled, 12 completed the study. One subject discontinued prior to completion due to severe erythema and local superficial forehead erosion at the site of MC lesion, which resolved with a 4-day course of a topical antibiotic ointment, resulting in slowly resolving hypopigmentation.

Of the twelve subjects who completed the study, 5 did not experience any local adverse effects. Adverse reactions were limited to application sites. The most common local adverse reaction, in 6 out of 12 patients, was mild to nominal erythema localized to some, but not all, of the treated molluscum contagiosum lesions. In two of these patients, both atopics, the erythema was moderate in one and severe in the other, and included the skin around only those MC lesions located in their antecubital fossae. Interestingly, these two atopic patients did not develop erythema at other treated sites. Of the 5 patients reporting pruritus at baseline, all reported complete or partial reduction by the end of the treatment. Two patients reported the onset of transient pruritus (one nominal, the other mild) during treatment. Less than 1 mm erosions of some of the lesions on 3 patients developed during the 4-week treatment course, one of who complained of pain. Two of 12 patients, neither with any erosions, complained of nominal to mild burning during topical therapy.

We failed to detect any evidence of systemic toxicity that could be attributable to any systemic interferon. None of the patients developed leukopenia, and none complained of headaches, chills or myalgias. One patient did experience a small rise of temperature at week 2 (T=37.8 °C), however physical exam at that visit revealed clinical signs of an upper respiratory infection. All but one patient applies less than one 250 mg sachet of imiquimod 5% cream per night (91 to 833 mg / m2 of body surface area / treatment with a mean of 258 mg / m2 / treatment). Complete resolution of the baseline target lesion occurred in 33% of subjects (4 out of 12) at the end of 4 weeks of treatment.


It has been reported that the spontaneous resolution rate of MC lesions at 1 year is 16%, [2] Although a benign skin infection, parents and physicians often opt to treat MC with standard destructive modalities in an attempt to curb innoculation to self and to others, for cosmesis, and to prevent secondary inflammation and bacterial infection of MC lesions. The addition of a non-destructive self-administered topical therapy for the treatement MC that is both safe and efficacious would be a favorable alternative.

Although there is a study reporting the use of imiquimod 1% cream for the treatment of MC in patients between 9 and 27 years of age [2], the safety and efficacy profile exclusively in children using the readily available higher concentration of imiquimod (5%) has not been reported. Because of the thinner strateum corneum and a decrease in total body surface area in children, the possibility of local or systemic toxicity with the use of imiquimod 5% cream was concerning.

In light of no systemic toxicity being detected, and an acceptable degree of localized irritation, the findings of this pilot study suggest that imiquimod 5% cream is a safe treatment in children with molluscum contagiosum Complete resolution of a baseline target lesion occurred in 33% of subjects (4 out of 12) at the end of 4 weeks of treatment, however the present study was not powered to address efficacy. Further studies are needed to determine the effectiveness and optimal dosing of imiquimod 5% cream in the treatment of molluscum contagiosum.


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