molluscum contagiosum

Molluscum contagiosum is a viral skin infection that is caused by molluscipoxvirus. It mainly affects children but it can affect adults too. Its appearance includes bumps that are raised, small and firm. It can commonly be found on the face, neck, arm, hands and genital area. In most cases, it is a self resolving condition which improves within 6-12 months.

Epidemiology

In children, the annual incidence of molluscum contagiosum ranges from 2-10% [1]
A large UK survey found that the average yearly incidence is 261 per 100,000 and over 80% of reported cases occurring in children under 15 years [2]
Sexual transmission affected young adults the most
The prevalence of the disease in HIV patients ranged from 5-33% [3]

Source: DermNetNZ.org

Molluscum contagiosum
Widely distributed lesions on the lower legs

Source: DermNetNZ.org

Molluscum contagiosum
Lesions seen on the face that vary is size and shape

Causes [4]
- Direct contact from skin-to-skin
- Contact with infected objects such as towels, bedding, furniture
- Sexual contact with infected people
- Bathing or swimming together as wet conditions are likely to spread the disease

Pathophysiology [5]
- Medical students
  - Molluscum contagiosum virus infects only the epidermis and replicates in the cytoplasm of epithelial cells.
  - Infection occurs through contact with infected individuals or contaminated objects, but the extent of epidermal injury required for infection is unknown.
  - The incubation period is usually 2-7 weeks, and the initial infection occurs in the basal layer of the epidermis.
  - Cellular proliferation leads to lobulated epidermal growths, resulting in the formation of molluscum bodies containing viral material at the center of lesions.
  - Inflammation and immune response may occur, especially in patients with compromised immune systems, such as HIV infection.
  - Molluscum contagiosum virus does not establish latency and evades the immune system through the production of virus-specific proteins.
  - Cell-mediated immunity is essential in controlling the infection, and humoral immunity does not seem to play a significant role in lesion regression.
  - Reinfection is common, and the virus is not strongly immunogenic, leading to infrequent antibody formation.
- Patients
  - Molluscum contagiosum virus infects only the outer layer of the skin and replicates in the cytoplasm (cell fluid) of epithelial cells.
  - Infection occurs through contact with infected individuals or contaminated objects, but the extent of epidermal injury required for infection is unknown.
  - The incubation period (the period between exposure to an infection and the appearance of the first symptoms) is usually 2-7 weeks, and the initial infection occurs in the basal layer of the epidermis (innermost layer of the epidermis).
  - Cellular proliferation (production and growth) leads to lobulated (globe shaped) epidermal growths, resulting in the formation of molluscum bodies containing viral material (infected by a virus) at the center of lesions (damaged skin).
  - Inflammation and immune response may occur, especially in patients with compromised immune systems, such as HIV infection.
  - Molluscum contagiosum virus does not establish symptom presentation and evades the immune system through the production of virus-specific proteins.
  - Cell-mediated immunity is essential in controlling the infection, and humoral immunity (involves the adaptive immune system triggered and changed with the presence of an infection) does not seem to play a significant role in lesion regression (decrease in severity)
  - Reinfection is common, and the virus is not strongly immunogenic (the ability of cells/tissues to provoke an immune response) leading to infrequent antibody formation.

Source: DermNetNZ.org

Molluscum contagiosum
Small cluster of lesions with some bursting

Source: DermNetNZ.org

Molluscum contagiosum
Small cluster of lesions on darker skin tones

Risk factors [6]
- Exposure to an infected person/object or sharing a personal item with someone who has infected
- Children with eczema
- Athletes in contact with others or share equipment
- Conditions that are warm, humid and crowded
- Patients with weakened immune systems

Presentations [7]
- Clusters of pink, dome shaped papules (spot)
- Smooth, waxy or pearly spots
- Found on the face, trunk (torso), hands, feet and genitalia regions
- Inflammation
- Itchiness
- Painless

Investigations [6]
- Clinical exam of the skin based on appearance
- May require a skin scraping to examine under the microscope to rule out infection or diagnose the condition
Differential diagnosis
- Herpes simplex virus
- Flat warts
- Chickenpox
- Nevi (moles)
- Milia- white spots
- Lichen planus- purple, flat topped bumps
- Follulitis- inflammation of the follicle seen with red bumps
- Acne vulgaris
- Tumours eg. basal cell carcinoma
- Fungal infections of the skin
- Keratoacanthoma- type of skin tumour that looks similar to the non-melanoma condition, squamous cell carcinoma [8,9]

Molluscum contagiosum

Smooth, skin- coloured and scattered lesions behind and below the ear

Management [10]
- Medical students
  - Reassure them that it is a self-limiting condition, and treatment is usually not required in immunocompetent individuals.
    - Spontaneous resolution typically occurs within 18 months.
    - Various treatment options are available, such as imiquimod cream, podophyllotoxin, and cryotherapy, but no single treatment has been proven highly effective.
  - Lifestyle changes
    - Advise on preventing infection spread by avoiding sharing towels, clothing, or bedding and refraining from scratching or squeezing lesions.
    - Exclusion from school, gym, or swimming is not necessary, but covering lesions with waterproof bandages before swimming is recommended if possible.
  - Manage any symptoms or complications, and consider referral to a specialist if needed.
  - Managing a person with anogenital molluscum contagiosum:
    - Reassure them that it is self-limiting, and treatment is usually not required in immunocompetent individuals.
    - Spontaneous resolution generally occurs within 18 months.
    - Physical or topical treatments like cryotherapy, podophyllotoxin, and imiquimod cream may be recommended, but evidence supporting their use is limited.
    - Give advice to prevent infection spread, including avoiding sharing personal items and refraining from scratching or squeezing lesions.
    - Exclusion from school, gym, or swimming is unnecessary, but waterproof bandages can be used to cover lesions before swimming.
    - For adults, advise against shaving or waxing the genital region to prevent further spread of lesions.
    - Condom use is recommended, but it may only offer partial protection.
  - Consider referring adults for screening for other sexually transmitted infections (STIs) and HIV.
  - In children, referral for suspected sexual abuse should only be arranged if other evidence suggests it.
- Patients
  - Reassure them that it is a self-limiting condition, and treatment is usually not required in individuals with health immune systems
    - Spontaneous resolution typically occurs within 18 months.
    - Various treatment options are available, such as imiquimod cream, podophyllotoxin, and cryotherapy (use of freezing to remove warts), but no single treatment has been proven highly effective.
  - Lifestyle changes
    - Advise on preventing infection spread by avoiding sharing towels, clothing, or bedding and refraining from scratching or squeezing lesions.
    - Exclusion from school, gym, or swimming is not necessary, but covering lesions with waterproof bandages before swimming is recommended if possible.
  - Manage any symptoms or complications, and consider referral to a specialist if needed.
  - Managing a person with anogenital (affects the anus and genitals) molluscum contagiosum:
    - Reassure them that it is self-limiting, and treatment is usually not required in immunocompetent individuals.
    - Spontaneous resolution generally occurs within 18 months.
    - Physical or topical treatments like cryotherapy, podophyllotoxin, and imiquimod cream may be recommended, but evidence supporting their use is limited.
    - Give advice to prevent infection spread, including avoiding sharing personal items and refraining from scratching or squeezing lesions.
    - Exclusion from school, gym, or swimming is unnecessary, but waterproof bandages can be used to cover lesions before swimming.
    - For adults, advise against shaving or waxing the genital region to prevent further spread of lesions.
    - Condom use is recommended, but it may only offer partial protection.
  - Consider referring adults for screening for other sexually transmitted infections (STIs) and HIV.
  - In children, referral for suspected sexual abuse should only be arranged if other evidence suggests it.

Molluscum contagiosum

Lesions can be large in size

Complications [9]
- Mental health problems and distress caused by appearance
- Itchiness (pruritis) and redness (erythema)
- Scarring
- Secondary bacterial infection
- Conjunctitivits
- Molluscum dermatitis- eczema surrounding the site of infection

Myths [11]
- Molluscum contagiosum is limited to undeveloped countries
- The condition is asymptomatic
- In all cases, the condition is self resolving so no treatment is required
Questions to ask your doctor
- Which conditions pose as a risk of spreading the condition?
- How do I know if my symptoms are getting worse?
- How long does treatment take before being effective?
- Who do I approach if I start showing signs of the complications of the condition?
- How is the condition prevented?
Support
- American Academy of Dermatology
- British Association of Dermatologists
- NHS