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Latest update 16/06/09
This chapter is set out as follows:
Aetiology
- Molluscum contagiosum is a common infection of the skin caused by a Poxvirus. It is largely, if not exclusively a human disease
- Infection with molluscum follows contact with infected persons or objects - the use of swimming pools appears to carry an increased risk. Sexual transmission of molluscum is also possible
Key diagnostic features
- Age of presentation – mainly in young children, although it rarely presents under the age of one year. There is also a later peak in young adults, some of which is attributable to sexual transmission
- Lesions are usually multiple but occasionally solitary lesions can be found
- Distribution
- Any part of the body can be affected
- In temperate parts of the world molluscum are commonly found on flexural skin such as the neck, the trunk – particularly around the axillae, the groin and behind the knees
- In the tropics lesions are most common on the limbs
- Patients with HIV who have widespread involvement often have considerable facial involvement
- Appearance
- Clusters of small shiny papules with an umbilicated centre
- Most papules are 2-5mm in size. Occasionally lesions can reach 1cm or greater in diameter, this is particularly so with solitary lesions
- As lesions resolve they become inflamed and crusty
- Lesions may arise in sites of skin injury and grow in a row, this is known as the Koebner phenomena
- Resolution - Most cases are self-limiting and last for 6-9 months, but some cases may last for up to 4 years
Additional information
- Infection of children though sexual abuse is presumably possible. However, to a greater extent than warts, molluscum is seen quite commonly on the genital and perineal skin, and abuse should not be regarded as the likely cause unless there are other suspicious features
- Lesions tend to be more numerous and last longer in patients with atopic eczema. In addition some patients with an atopic tendency develop patchy eczema around areas of molluscum
- Widespread lesions can be associated with immunosuppressed patients and sarcoidosis
Management
- Provide a patient information leaflet
- Cryotherapy is a very effective treatment. Often only a single freeze-thaw cycle of 5-10 seconds is needed
- In young children cryotherapy is rarely tolerated and the parents of such children should be encouraged to let the condition runs it natural course
- Curettage for histology may be needed for larger solitary lesions where there is diagnostic uncertainty
- Eczematous areas needed to be treated as for normal eczema
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Figure 1 - Mollusum contagiosum
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Figure 2 - Molluscum contagiosum on the inner arm |
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