Molluscum contagiosum (MC) is a skin infection which commonly affects children. It is typically harmless and self-limiting, requiring no further treatment. However, there are cases where this infection can be seen in adults, but its presentation differs from when it occurs in children. The purpose of this article is to explain the causes, symptoms, diagnosis and management of MC and when medical attention is required.

What is molluscum contagiosum?

MC is essentially a viral skin infection caused by the MC virus, belonging to the poxvirus family. It produces small, raised bumps on the skin’s surface filled with white coloured fluid. However, as MC is viral, it has its lifespan and resolves by itself with time. (1-2) A common misconception, however, is that MC only affects children. Although it is true that MC largely affects children, this does not mean that adults are immune to this issue.³

When MC occurs in adults, the presence of bumps on the skin can be considered unsightly, and the contagious nature of molluscum contagiosum can affect daily activities due to the risk of infection transmission to others. Furthermore, some adults may be suffering from existing health issues that can worsen or prolong MC.^3,4

What are the symptoms of molluscum contagiosum?

The primary symptom of Molluscum contagiosum is the appearance of small, raised dome-shaped, spherical bumps known as papules. These papules are usually 2-5 mm in size, and there are usually fewer than 20 papules across the body. These papules have a dimple in the centre and are typically white, but can also be pink or purple or the same colour as the skin and contain a whitish fluid inside. These papules can be soft initially, but over time can harden, and the skin can be itchy.^1,4

Figure 1: Molluscum contagiosum presentation on skin.

MC bumps in adults are often between 2mm and 6mm in diameter, but they can grow larger, up to 10mm to 20mm. There are typically fewer than 20 molluscum bumps on the body; however, in some rare instances, people have reported over 100 bumps.⁵

MC can occur anywhere on the skin but commonly affects the arms, legs and face. It generally lasts for up to 18 months, but is self-limiting and fades by itself and doesn’t usually require treatment. However, it is contagious and can spread easily to others.²

How does molluscum contagiosum spread?

MC spreads via direct skin-to-skin contact. It can also be spread via contact with contaminated items due to living in proximity in bedrooms and shared housing. Or via close contact due such as via participation in contact sports or activities.³ MC can also spread via shaving and waxing, as this spreads the virus and viral fluid to other skin areas.⁶

In adults, however, it can also be spread via sexual contact and transmission. Therefore, adults can present with MC in the genital regions, which differs from its presentation in children and infants. Furthermore, adults who already suffer from existing health concerns, such as atopic eczema or those who have a compromised immune system due to immunosuppressant treatment, such as steroids or illnesses such as HIV or SLE, are at an increased risk of further complications.⁷

How is MC diagnosed?

MC is diagnosed via a physical examination with a healthcare professional, such as a doctor, nurse or pharmacist or via a local GUM clinic (if genital regions are affected), is enough to diagnose someone with MC.  In some cases, a biopsy or skin sample may be taken to rule out other causes if in doubt, as MC can resemble other skin concerns such as acne, chicken pox, skin cancer or warts.^1,3

How is MC treated?

Usually, MC does not require any specific treatment as MC resolves by itself within 18 months.^1,2

However, treatment can be considered in certain circumstances, particularly in adults where papules are affecting a patient’s quality of life, such as mental health, as MC can make a person feel self-conscious.^3,4

Options for treatment include physical removal via cryotherapy, surgical removal or laser treatment.  Or via topical treatments with agents to dissolve the papules, such as retinol, salicylic acid or potassium hydroxide.⁴

Another option is via drug treatment with an antiviral such as imiquimod in the form of gels, creams or liquids to kill the MC cytomegalovirus and eliminate the infection. However, treatment with an antiviral agent is generally only required in patients who have a compromised immune system, where MC has the risk of becoming a systemic infection affecting the entire body and may also cause further complications.⁴

Complications of MC in adults

MC, although generally well controlled, does have the potential, like any illness, for potential complications. This includes secondary infections where papules can become infected with a bacterial infection as a result of inflammation or irritation due to scratching or injury, where bacterial infiltration into the skin layers may occur.

There is also the risk of scarring due to scratching or physical or chemical treatment of the papules, which can be potent.⁶

There is also the mental health and social impact that MC may cause.  Papules may develop on areas of the body which are visible to others. Adults may become embarrassed as others may see them. It can also affect personal relationships, especially if MC is affecting the genital areas, as there is the risk of sexual transmission to others, which can make intimacy difficult.^6,7

MC in immunocompromised patients

In healthy individuals, MC resolves without any further issues. However, in patients with a weakened immune system, MC has the potential to cause further complications. There is the risk of secondary infections on top of the initial MC, and MC itself can transform into a more severe and widespread infection. 

Patients who are immunocompromised include those suffering from illnesses that weaken the immune system, such as HIV/AIDS or IBD or those who are on medication that can suppress the immune system, such as DMARDs, steroids or biological agents.

Complications in immunocompromised adults from MC include:

• More lesions: MC papules are small and raised and appear in numbers generally less than 20. However, in individuals with a weak immune system, they can proliferate significantly and become vast in number, more so than in a healthy individual
• Longer disease duration: As the immune system is weak, this means that infections take a longer time to resolve, and the body takes a longer time to heal. MC is also no different. On average, 6-12 months is when MC resolves in healthy individuals. In those who are immunocompromised, MC can take years to clear and even longer if secondary infections such as impetigo or conjunctivitis have developed on top of the initial MC
• Treatment resistance: In addition to the immune system being weak, the MC treatment used may also not have the desired effect that it would in an otherwise healthy individual. In many cases, treatment can not work, or work very minimally, and increased or sometimes maximum doses of a drug may need to be administered. In MC cases which are very resistant to treatment, multiple medication therapies may be required to treat MC. As treatment with a single agent may be low. This issue may be further compounded if additional infections from the MC also show resistance
• Atypical presentation: In immunocompromised individuals, MC appears differently. The papules have a greater size or imitate other diseases, particularly cancers such as basal cell carcinoma or keratocanthoma if they are a single lesion. Or infectious diseases, such as histoplasmosis or cryptococcosis if the lesions are extensive^7,8

Therefore, such patients who have a background illness that weakens the immune system and can make MC worse should be diagnosed and managed early to prevent this with a personalised treatment plan.

Complications of MC in immuno- compromised patients include:

• Secondary skin infection, such as Impetigo
• Cellulitis
• Conjunctivitis if MC has affected the eyelids
• Abscess/boil on area of papules⁶

Preventing the spread of MC

MC can spread easily from skin-to-skin contact and contact with infected surfaces. It is important to ensure that one maintains good hygiene. 

Good hygiene measures include:

• Avoid sharing items such as towels, flannels, clothes, hair brushes, and makeup brushes
• Avoid close contact with others to prevent skin-to-skin contact or transmission of fluid from papules
• Avoiding squeezing or scratching papules as this contains the virus; if skin is very itchy, an oral antihistamine can be tried. This can be obtained from a local pharmacy or GP
• Covering MC papules to prevent skin-to-skin contact with others
• Avoiding laser treatments or shaving
• Abstaining from sexual activity until a confirmed diagnosis of MC from a health professional to prevent spreading MC via sexual contact if papules in the genital regions
• Avoiding communal swimming baths, saunas and sunbeds
• Seeing a health professional as soon as possible if one suspects MC, especially if suffering from another condition such as atopic eczema or psoriasis, that can worsen MC. As well as those who have a weak immune system or are in close contact with someone who is⁹

Summary

MC is a viral infection mainly affecting children but can also occur in adults. It is largely self-limiting and resolves by itself, however, in patients who are immunocompromised, it can be more problematic and can lead to further complications. Therefore, it is important that if one suspects MC, they should see a healthcare professional to diagnose this and assess and manage this further if required.