Introduction 

Have you ever noticed small, painless pearly bumps on your or your child’s skin and wondered what they could be? This could be a sign of the common and harmless skin condition called Molluscum contagiosum which is caused by a poxvirus.¹ Molluscum contagiosum is a common viral disease spread via direct contact, and it mainly affects younger children and infants. Clinically Molluscum contagiosum can appear as small pearly papules (bumps) and range both in size from around 1mm to 6mm and even in colour appearing as either white, pink or brown. The papules may be found in areas like the armpit, genital area or behind the knees and each papule produces a white cheesy material.² Now after recognising the disease, we can take a closer look at the different ways it is treated. 

Does molluscum contagiosum always need to be treated? 

No, in most healthy individuals the disease will self-resolve when left untreated within 6 months to 2 years but this time length may vary depending on the number, location and size of the papules. Whilst the papules are still present, you are still considered infectious and so to reduce the spreading of the disease it is important to prioritise hygiene in the form of frequent hand washing, avoiding scratching the bumps, and in infected adults avoiding sexual activity. Once the papules have disappeared, you are no longer contagious.³ 

When is treatment necessary? 

Usually, treatment is needed in patients with weakened immune systems such as those on chemotherapy or who have HIV/AIDS, in these patients the disease can be more systemic and severe. Additionally, you may want to seek medical treatment individually to speed up the resolution of the infection and reduce the likelihood of scarring^.4

Physical treatments 

Cryotherapy 

What is cryotherapy? 

Cryotherapy also known as freezing is a quick and common method of using extremely cold substances known as cryogens to remove the molluscum contagiosum bumps. The most common cryogen used is liquid nitrogen. Dry ice and Dimethyl ether and propane (DMEP) are other alternatives.

The cryogen is applied to the papule for a few seconds where it causes deep tissue necrosis and death of the virus causing Molluscum Contagiosum. This treatment is often repeated in 2-3 week intervals.⁵

What side effects may you experience with cryotherapy? 

Immediate: 

• Pain
• Tingling sensation 
• Swelling
• Headache 
• Blisters 

Delayed 

• Bleeding 
• Secondary infection 
• Local nerve damage 
• Ulceration 
• Scarring⁶

Curettage 

What is curettage? 

Another method of removal is Curettage, where the skin lesion is scraped off, and it is used when the lesion is softer than the surrounding tissue. 

A curette is a small spoon with sharp edges used to gently scrape off the skin lesion. Anaesthetic cream is recommended to be applied beforehand as the procedure can be quite painful. The treated area is then bandaged so that the healthy skin can reform. Manual extrusion is a similar method to this, it involves the removal of the papule using instruments such as a needle, forceps or scalpel. Compared with curettage it is more easily accessible, but it can lead to scarring. 

What side effects may you experience with Curettage? 

• Redness and swelling 
• Scarring 
• Pain 
• Infection⁷

Laser ablation 

What is laser ablation? 

This is another physical treatment which uses high-intensity light energy to focus on and remove the papules. The aim of this therapy is to destroy the papules without harming the surrounding tissue. Pulsed dye lasers are frequently used, which have excellent results as they are less likely to lead to scarring. However, a clear disadvantage of this method is that it is less cost-effective in comparison with other therapies.⁵

What side effects may you experience with Laser ablation? 

• Temporary redness, pain, blisters and crusting 
• Secondary infections 
• Pigment changes and scarring⁸

Oral and topical medications

Alternatively, various types of medical treatment can be used to treat Molluscum Contagiosum. These include: 

Cimetidine

What is cimetidine? 

Cimetidine is an oral drug known as a histamine 2- receptor antagonist, which means it stimulates the body’s immune system to fight off the Molluscum Contagiosum virus and treats the widespread lesions.⁵ The benefits of this drug is that it is a less painful approach, it is less likely to leave scars, and it can be administered from the comfort of your own home.¹

What is the dosage of cimetidine for the treatment of molluscum contagiosum? 

For children, the dosage is between 30-40 mg/kg/day in two divided doses for 2 months and for adults it is usually lower in comparison with a child, but specific dosages are determined by a healthcare professional.⁹

What side effects may you experience with cimetidine? 

Usually, these are rare: 

• Nausea 
• Rash 
• Dizziness 
• Diarrhoea ⁹

What else is important to consider with cimetidine? 

In patients with facial Molluscum Contagiosum, Cimetidine is less effective so a topical treatment should be considered instead. Additionally, this drug may interact with several other medications, so it is important for your physician to review your medication before initiating the drug.¹

Cantharidin

What is cantharidin? 

This is a successful treatment for Molluscum Contagiosum. It is a substance produced by a blister beetle known as the Cantharis vesicatoria. It is applied to the papule and then covered with tape. It works by creating a blister and is left for at least four hours before washing off with soap and water.¹⁰ The blister over the next couple of days will dry and may also lift the papule off.³ This substance only penetrates the epidermal layer of the skin which means there is less chance of scarring. Usually, 1-3 treatments are necessary to completely remove the lesion.¹⁰

What are the side effects of cantharidin? 

• A blister may be uncomfortable 
• This may lead to small satellite warts around the original virus 
• May cause severe blistering, so should not be used on the face and should be tested on the individual beforehand.¹⁰

Podophyllotoxin cream

What is podophyllotoxin cream? 

Podophyllotoxin cream works by preventing the replication and multiplication of the Molluscum Contagiosum; these substances are known as antimitotic. This medication however should be used with caution and only as directed due to its potential harm to healthy skin cells.¹¹

After washing the affected area and then left to dry, the cream should be applied with a cotton-tipped applicator¹², and this should be repeated twice daily for 3 consecutive days for a maximum of 5 weeks or until the papule has disappeared.¹¹

What are the side effects of podophyllotoxin cream? 

Local effects 

• Local irritation due to necrosis of the papule 
• Redness, the itch of the surrounding skin 
• Superficial ulcerations 
• Bleeding 
• Scarring and erosive damage

Systemic effects 

• Peripheral nerve damage 
• Renal damage 
• Dizziness 
• Headache 
• Vomiting 

The substance is also contraindicated in pregnancy due to harmful effects on the foetus and should not be used on open wounds.⁵

Imiquimod

What is Imiquimod? 

Imiquimod is another topical cream typically used at a concentration of 5% to treat Molluscum Contagiosum and is available solely for adult populations. Currently, it is not recommended in children due to the possible side effects.¹ It works by stimulating the production of substances called cytokines such as interferon- alpha which works to stimulate the immune system to act against the virus. The cream is applied to the affected area nightly and rinsed off in the morning for 4 weeks.⁵

What are the side effects of Imiquimod? 

Common: 

• Localised redness
• Hard and flaky skin,
• Itching and stinging
• Erosions 

Less common 

• Headache
• Flu-like symptoms
• Nausea and diarrhoea.

 The side effects should usually resolve after 2 weeks of stopping the medication.¹²

Salicylic acid

What is salicylic acid ? 

Salicylic acid is also used together with iodine solution. A 10 % iodine solution is applied to the papules, and then once dry it is covered with a 50 % salicylic acid tape. The Salicylic acid softens the keratin, which is a protein in the skin and makes the upper layer of skin erythematous and easier to remove.⁵

What are the side effects of salicylic acid?

• Severe skin irritation
• Reddening of the skin
• Erosions and flushing 

It should not usually be given to children under 2 years of age.¹³

Other topical treatments 

Similar topical treatments are Potassium hydroxide which works by breaking down the Molluscum Contagiosum papule so that it can be destroyed by the immune system and Tretinoin which may make your skin more sensitive to sunlight and UV, so apply with caution.¹² 

Interferon alpha

What is interferon alpha?

Interferon alpha is a type of treatment which is used in cases of Molluscum Contagiosum, which are severe and resistant to conventional treatments, especially in immunocompromised patients.¹ 

Interferon alpha works by enhancing the immune cell response to the virus, inhibiting the replication of the virus and helping immune cells to recognise viral cells more easily is known as modulation.¹⁴

It may be used topically or as intralesional injections which are used to treat face papules.¹

What are the side effects of Interferon alpha?

Interferon alpha can have unpleasant side effects including:

• Pain
• Site tenderness
• Tiredness 
• Depression.

Due to these side effects interferon treatment although effective for the immunocompromised is not appealing from a patient perspective.¹

Summary 

Molluscum Contagiosum describes a common viral condition characterised by small painless pearly bumps. It is most commonly found in paediatric populations and spread through direct contact. There are several methods of treatment but in most cases, Molluscum Contagiosum self-resolves within 6 months to 2 years. Traditional forms of treatment include physical treatment, oral drugs, topical creams and solutions which have various mechanisms of action and side effects. The most effective medication to treat Molluscum Contagiosum in immunocompromised patients such as those with HIV/AIDS is Interferon alpha, which can be applied topically or as intralesional injections.