Molluscum contagiosum

2020 European guideline on the management of genital molluscum contagiosum

Molluscum contagiosum is a benign viral epidermal infection associated with high risk of transmission. The guideline is focused on the sexually transmitted molluscum contagiosum. The diagnosis is clinical with characteristic individual lesions, termed 'mollusca', seen as dome-shaped, smooth-surfaced, pearly, firm, skin-coloured, pink, yellow or white papules, 2 - 5 mm in diameter with central umbilication. Dermoscopy may facilitate diagnosis. Therapeutic options are numerous, including physical treatments (cautery, curettage and cryotherapy), topical chemical treatments (e.g. podophyllotoxin and imiquimod) or waiting for spontaneous resolution in immunocompetent patients. In pregnancy, it is safe to use physical procedures (e.g. cryotherapy). Immunosuppressed patients develop severe and recalcitrant molluscum lesions that may require treatment with cidofovir, imiquimod or interferon. Patients with molluscum contagiosum infection should be offered to be screened for other sexually transmitted infections.

Interventions for cutaneous molluscum contagiosum

BACKGROUND

Molluscum contagiosum is a common skin infection that is caused by a pox virus and occurs mainly in children. The infection usually resolves within months in people without immune deficiency, but treatment may be preferred for social and cosmetic reasons or to avoid spreading the infection. A clear evidence base supporting the various treatments is lacking.This is an update of a Cochrane Review first published in 2006, and updated previously in 2009.

OBJECTIVES

To assess the effects of specific treatments and management strategies, including waiting for natural resolution, for cutaneous, non-genital molluscum contagiosum in people without immune deficiency.

SEARCH METHODS

We updated our searches of the following databases to July 2016: the Cochrane Skin Group Specialised Register, CENTRAL, MEDLINE, Embase, and LILACS. We searched six trial registers and checked the reference lists of included studies and review articles for further references to relevant randomised controlled trials. We contacted pharmaceutical companies and experts in the field to identify further relevant randomised controlled trials.

SELECTION CRITERIA

Randomised controlled trials of any treatment of molluscum contagiosum in people without immune deficiency. We excluded trials on sexually transmitted molluscum contagiosum and in people with immune deficiency (including those with HIV infection).

DATA COLLECTION AND ANALYSIS

Two review authors independently selected studies, assessed methodological quality, and extracted data from selected studies. We obtained missing data from study authors where possible.

MAIN RESULTS

We found 11 new studies for this update, resulting in 22 included studies with a total of 1650 participants. The studies examined the effects of topical (20 studies) and systemic interventions (2 studies).Among the new included studies were the full trial reports of three large unpublished studies, brought to our attention by an expert in the field. They all provided moderate-quality evidence for a lack of effect of 5% imiquimod compared to vehicle (placebo) on short-term clinical cure (4 studies, 850 participants, 12 weeks after start of treatment, risk ratio (RR) 1.33, 95% confidence interval (CI) 0.92 to 1.93), medium-term clinical cure (2 studies, 702 participants, 18 weeks after start of treatment, RR 0.88, 95% CI 0.67 to 1.14), and long-term clinical cure (2 studies, 702 participants, 28 weeks after start of treatment, RR 0.97, 95% CI 0.79 to 1.17). We found similar but more certain results for short-term improvement (4 studies, 850 participants, 12 weeks after start of treatment, RR 1.14, 95% CI 0.89 to 1.47; high-quality evidence). For the outcome 'any adverse effect', we found high-quality evidence for little or no difference between topical 5% imiquimod and vehicle (3 studies, 827 participants, RR 0.97, 95% CI 0.88 to 1.07), but application site reactions were more frequent in the groups treated with imiquimod (moderate-quality evidence): any application site reaction (3 studies, 827 participants, RR 1.41, 95% CI 1.13 to 1.77, the number needed to treat for an additional harmful outcome (NNTH) was 11); severe application site reaction (3 studies, 827 participants, RR 4.33, 95% CI 1.16 to 16.19, NNTH over 40).For the following 11 comparisons, there was limited evidence to show which treatment was superior in achieving short-term clinical cure (low-quality evidence): 5% imiquimod less effective than cryospray (1 study, 74 participants, RR 0.60, 95% CI 0.46 to 0.78) and 10% potassium hydroxide (2 studies, 67 participants, RR 0.65, 95% CI 0.46 to 0.93); 10% Australian lemon myrtle oil more effective than olive oil (1 study, 31 participants, RR 17.88, 95% CI 1.13 to 282.72); 10% benzoyl peroxide cream more effective than 0.05% tretinoin (1 study, 30 participants, RR 2.20, 95% CI 1.01 to 4.79); 5% sodium nitrite co-applied with 5% salicylic acid more effective than 5% salicylic acid alone (1 study, 30 participants, RR 3.50, 95% CI 1.23 to 9.92); and iodine plus tea tree oil more effective than tea tree oil (1 study, 37 participants, RR 0.20, 95% CI 0.07 to 0.57) or iodine alone (1 study, 37 participants, RR 0.07, 95% CI 0.01 to 0.50). Although there is some uncertainty, 10% potassium hydroxide appears to be more effective than saline (1 study, 20 participants, RR 3.50, 95% CI 0.95 to 12.90); homeopathic calcarea carbonica appears to be more effective than placebo (1 study, 20 participants, RR 5.57, 95% CI 0.93 to 33.54); 2.5% appears to be less effective than 5% solution of potassium hydroxide (1 study, 25 participants, RR 0.35, 95% CI 0.12 to 1.01); and 10% povidone iodine solution plus 50% salicylic acid plaster appears to be more effective than salicylic acid plaster alone (1 study, 30 participants, RR 1.43, 95% CI 0.95 to 2.16).We found no statistically significant differences for other comparisons (most of which addressed two different topical treatments). We found no randomised controlled trial evidence for expressing lesions or topical hydrogen peroxide.Study limitations included no blinding, many dropouts, and no intention-to-treat analysis. Except for the severe application site reactions of imiquimod, none of the evaluated treatments described above were associated with serious adverse effects (low-quality evidence). Among the most common adverse events were pain during application, erythema, and itching. Included studies of the following comparisons did not report adverse effects: calcarea carbonica versus placebo, 10% povidone iodine plus 50% salicylic acid plaster versus salicylic acid plaster, and 10% benzoyl peroxide versus 0.05% tretinoin.We were unable to judge the risk of bias in most studies due to insufficient information, especially regarding concealment of allocation and possible selective reporting. We considered five studies to be at low risk of bias.

AUTHORS' CONCLUSIONS

No single intervention has been shown to be convincingly effective in the treatment of molluscum contagiosum. We found moderate-quality evidence that topical 5% imiquimod was no more effective than vehicle in terms of clinical cure, but led to more application site reactions, and high-quality evidence that there was no difference between the treatments in terms of short-term improvement. However, high-quality evidence showed a similar number of general side effects in both groups. As the evidence found did not favour any one treatment, the natural resolution of molluscum contagiosum remains a strong method for dealing with the condition.

Epidemiology and impact of childhood molluscum contagiosum: a case series and critical review of the literature

Parents of 30 children with clinically diagnosed molluscum contagiosum were surveyed to assess their perception of the condition, its treatment, its impact on their everyday lives, and on the children themselves. Among parents, 82% reported that molluscum contagiosum concerned them moderately or greatly. Concerns focused on physical issues associated with the infection, such as scarring, itching, chance of spread to peers, pain, and the effects of treatments. Quality of life was not affected. Molluscum contagiosum was most common among school-age children. Eighteen of 29 respondents swam in public pools, a common activity in children of this age. All epidemiologic studies of molluscum contagiosum in otherwise healthy individuals, published since 1966, have been critically reviewed herein. The review confirms an association between swimming pool use and molluscum contagiosum. Age, living in close proximity, skin-to-skin contact, sharing of fomites, and residence in tropical climates were also associated with higher rates of infection while sex, seasonality, and hygiene showed no such association.