What is molluscum contagiosum?
Molluscum contagiosum is a viral infection that results in a typical skin rash. It is most common in children, particularly between 1 and 10 years of age. It is a very common virus that most children are exposed to but only some express. It is also a common finding in patients who are immunosuppressed, most typically in patients with HIV disease. These two groups in the population are most likely to develop an active infection due to their immune function. For children the immune system is immature and does not initially recognise the virus as foreign. The reason for this is that the virus is located quite superficially on the skin surface and develops a reaction within the surrounding skin that hides the viral particles from the immune system. For patients who are immunosuppressed the virus can reactivate as the mechanism to attack the virus within the immune system is dampened.
What are the signs of an active infection?
The virus presents with a rash often commencing on the lower abdomen, back, buttocks or thighs. It can then spread to involve the limbs and the face. The rash is composed of skin coloured papules that have a central dell. The papules are described as umbilicated as they resemble the shape of an umbilicus. The papules can present as solitary lesions but more often there are clusters of the papules on different areas of the body. The papules are not usually itchy, but can be, especially if there is associated dermatitis. The papules are usually only a few millimetres in size but occasionally large lesions up to 1-2 centimetres can develop. Occasionally the papules can become infected.
How is molluscum contagiosum spread?
Molluscum contagiosum, as the name suggests, is quite contagious and often spreads within families to other siblings. It is particularly well transmitted in warm water and thus spreads when children share baths. This is the reason for the initial cluster of lesions seen on the lower abdomen or back at the level of the bath water. The lesions can be spread to other areas of the body through scratching and then touching other parts of the body.
How is molluscum contagiosum treated?
There is no need to actively treat molluscum contagiosum in children. The virus will resolve when the immune system recognises the virus and at that stage all lesions disappear. The most important thing for parents to do is to try and avoid transmission to siblings by not bathing together or sharing towels. Children are not to be excluded from school as the virus is ubiquitous such that people will be exposed even if children exhibiting signs of active infection are kept home. Resolution can take months and in some cases more than one year. There are a few techniques that sometimes hasten the resolution of the infection. These techniques all aim to produce mild irritation around the papules to draw the immune system to the area to help with recognition of the virus. A very simple technique that can be used is tape stripping. This is when an adhesive tape is applied to a few of the lesions at night and then pulled off in the morning to create a small amount of erythema without trauma to the skin. If there is dermatitis within the area and this is itchy then a topical corticosteroid may be used. If there is any doubt about the diagnosis, then an expert opinion should be sought.
If you would like to make contact with the Australasian College of Dermatologists you may do so via the following contact details:
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Telephone: (02) 8741 4101