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Molluscum contagiosum is a viral skin infection caused by the molluscum…
Molluscum contagiosum is a viral skin infection caused by the molluscum contagiosum virus (MCV), which is classified within the family of poxviruses (Poxviridae)
risk
Close contact with an infected person — transmission occurs by direct contact with infected skin (sexual, non-sexual, or autoinoculation) or indirectly via contaminated fomites (such as shared towels and flannels) [Gerlero, 2018; Meza-Romero, 2019]. Vertical transmission has also been
Atopic dermatitis — people with atopic dermatitis are more likely to develop infections with molluscum contagiosum due to impaired skin barrier function and immune dysregulation. The prevalence of molluscum contagiosum in children with atopic dermatitis is estimated to be between 20–45% [BMJ, 2021] compared with 5–12% in children who do not have the condition.
Immunocompromize — molluscum contagiosum is particularly problematic in adults who are immunocompromized. The main causes of immunosuppression associated with molluscum contagiosum include HIV infection, solid organ transplants, immunosuppressive therapy, systemic lupus erythematosus, sarcoidosis, and neoplasia. Giant nodules of molluscum contagiosum have been described as a first clinical manifestation of HIV infection.
Climate — molluscum contagiosum is more common in geographical areas with warm climates [Olsen, 2014a; Leung, 2017; BMJ, 2021].
Swimming — there is evidence for an association between swimming and molluscum contagiosum infection [Olsen, 2014a; BMJ, 2021].
The diagnosis of molluscum contagiosum is predominantly clinical, as the classic appearance of the lesions usually excludes other conditions, such as warts. Diagnostic investigations are not usually necessary.
Typically, the person presents with lesions which have developed over a few weeks.
The lesions are usually characteristic, presenting as smooth-surfaced, firm, dome-shaped, flesh-coloured or pearly white papules with a central umbilication.
Commonly, people have 1–30 individual lesions at a time, occurring as clusters (which can become koebnerised). Occasionally, solitary lesions can be seen.
Molluscum lesions are usually 2–5 mm in diameter. Occasionally, much larger (giant mollusca) lesions (1 cm or greater in diameter) can be seen, especially with solitary lesions or in the setting of immunocompromize.
Almost any part of the body can be affected:
In children, lesions are commonly seen on the trunk and in flexures, but anogenital lesions may also occur.
In adults, sexual contact may lead to lesions developing on the genitalia, pubis, thighs, and lower abdomen.
Rarely, lesions can occur on the soles of the feet, palms of the hands, oral mucosa, and eyelids.
Immunocompromized people (for example those with HIV) or people on immunosuppressants (such as oral corticosteroids) can present with facial, widespread (often numbering over 100), or atypical lesions.
Atypical presentations may include giant, cystic, ulcerated, follicular, condyloma acuminatum-like, sebaceous naevus-like, pyogenic granuloma-like, cellulitis or abscess-like lesions.
Molluscum lesions are frequently asymptomatic, but complications (such as pruritus, erythema and bacterial superinfection) may occur
Eczema or inflammation can develop around lesions prior to resolution. It is important to differentiate this from inflammation from eczema or a bacterial skin infection, both of which may require treatment.
Differential diagnoses of molluscum contagiosum include:
Acne vulgaris.
Infections, such as common warts (verruca vulgaris), chicken pox, folliculitis, and condyloma acuminatum. See the CKS topics on Warts - anogenital and Warts and verrucae.
Milia.
Keratoacanthoma.
Cutaneous horn.
Tumours, such as basal cell carcinoma and syringomas.
Papular urticaria.
Lichen planus (uncommon).
Deep fungal infection, including penicilliosis, cryptococcosis, histoplasmosis, coccidiodomycosis, pneumocystis carinii, and aspergillosis.
Differential diagnoses of genital molluscum include:
Ectopic sebaceous glands.
Vulvar lymphangioma circumscriptum.
Genital warts.
Differential diagnoses of giant molluscum contagiosum include:
Acantholytic acanthoma.
Epidermoid cyst.
Subepidermal calcified nodule.
Abscess.
Keratoacanthoma.
Cutaneous horn.
When should I refer a person with molluscum contagiosum
?
Arrange urgent referral to an HIV specialist for people with HIV infection who have extensive molluscum lesions.
Arrange urgent referral to opthalmology for people with eyelid-margin or ocular lesions and associated red eye. People with mild eyelid lesions may be managed in primary care or by an optometrist.
Refer adults with anogenital lesions to genito-urinary medicine for screening for other sexually transmitted infections.
In children, lesions are commonly seen in anogenital areas, but referral for suspected sexual abuse should only be arranged if there is other evidence to suggest this. For more information, see the section on Sexual abuse in the CKS topic on Child maltreatment - recognition and management.
Consider referring to a dermatologist if:
There is diagnostic uncertainty.
The person is known to be immunocompromized.
Lesions are extensive and painful (although inflamed lesions may indicate resolution).
How should I manage a person with non-genital molluscum contagiosum?
Provided referral is not indicated:
Reassure the person that molluscum contagiosum is a self-limiting condition.
Treatment is not usually required in immunocompetent people,and spontaneous resolution usually occurs within 18 months.
Several treatment options exist for molluscum contagiosum, such as imiquimod 5% cream, podophyllotoxin 0.5% (off-label indication), and cryotherapy. However, no single treatment has been shown to be convincingly effective in treating molluscum infection in immunocompetent people.
Give general advice to avoid spread of the infection.
Explain that lesions are contagious and they should avoid sharing towels, clothing, or bedding until lesions resolve.
Encourage people not to scratch or squeeze the lesions, to avoid spread of the infectious material and also reduce the risk of superinfections.
Advise that exclusion from school, gym, or swimming is not necessary. If possible, lesions should be covered with waterproof bandages or clothes prior to using swimming pools.
Manage any symptoms or complications, or refer to a specialist if necessary.
Eczema or inflammation can develop around lesions prior to resolution. It is important to differentiate this from inflammation from eczema or a bacterial skin infection, both of which may require treatment.
For more information, see the sections on the treatment of flares (mild, moderate or severe) and treatment of infected eczema in the CKS topic on Eczema - atopic.
Provide sources of additional information, such as:
The NHS website: Molluscum contagiosum.
The British Association of Dermatologists:
Molluscum contagiosum.
Molluscum contagiosum in children.
How should I manage a person with anogenital molluscum contagiosum?
Provided referral is not indicated:
Reassure the person that molluscum contagiosum is a self-limiting condition.
Treatment is not usually required in immunocompetent people, and spontaneous resolution usually occurs within 18 months.
Physical or topical treatment, such as cryotherapy, podophyllotoxin 0.5% (off-label indication), and imiquimod 5% cream may be recommended for people with anogenital molluscum. However, there is a lack of evidence to support their use.
Give general advice to avoid spread of the infection.
Explain that lesions are contagious and they should avoid sharing towels, clothing, or bedding until lesions resolve.
Encourage people not to scratch or squeeze the lesions, to avoid spread of the infectious material and also reduce the risk of superinfections.
Advise that exclusion from school, gym, or swimming is not necessary. If possible, lesions should be covered with waterproof bandages or clothes prior to using swimming pools.
In adults with anogenital lesions:
Also advise that they should avoid shaving or waxing their genital regions, to prevent further spread of lesions (by autoinoculation).
Advise that they should use condoms, although this may only offer partial protection as transmission may still occur by skin-to-skin contact.
Refer to genito-urinary medicine for screening for other sexually transmitted infection (STIs), including HIV.
In children with anogenital lesions, referral for suspected sexual abuse should only be arranged if there is other evidence to suggest this.
For more information, see the section on Sexual abuse in the CKS topic on Child maltreatment - recognition and management.
Manage any symptoms or complications, or refer to a specialist if necessary.
Eczema or inflammation can develop around lesions prior to resolution. It is important to differentiate this from inflammation from eczema or a bacterial skin infection, both of which may require treatment.
For more information, see the sections on the treatment of flares (mild, moderate or severe) and treatment of infected eczema in the CKS topic on Eczema - atopic.
Provide sources of additional information, such as:
The NHS website: Molluscum contagiosum.
The British Association of Dermatologists:
Molluscum contagiosum.
Molluscum contagiosum in children.