Molluscum Contagiosum

Molluscum contagiosum (MC), also known as water warts, is a viral infection of the skin caused by the molluscum contagiosum virus (MCV), a member of the poxvirus family. This condition is characterised by small, raised, pink lesions with a dimple in the centre. The infection is highly contagious and spreads through direct contact or via contaminated objects. Although it affects individuals of all ages, it is most common in children aged one to ten years.

Signs and Symptoms

MC lesions are typically flesh-coloured, dome-shaped, and pearly in appearance, ranging from 1-5 mm in diameter with a characteristic dimpled centre. In children, lesions are most commonly found on the face, arms, legs, torso, and armpits. Adults may have lesions in the genital region, often categorised as a sexually transmitted infection. While these lesions are generally not painful, they may itch or become irritated. Scratching can lead to the spread of the virus, secondary bacterial infections, and scarring. In some cases, eczema may develop around the lesions.

Transmission

MC is highly contagious and can be transmitted through various means, including direct skin contact, contact with contaminated surfaces (fomites), or autoinoculation by scratching or picking the lesions and then touching other parts of the skin. Children are particularly susceptible to autoinoculation, leading to widespread clusters of lesions.

Diagnosis

Diagnosis is primarily based on the appearance of the lesions. The virus cannot be routinely cultured, but a diagnosis can be confirmed by excisional biopsy. Histologically, MC is characterised by molluscum bodies (Henderson-Patterson bodies) in the epidermis, above the stratum basale. These bodies consist of cells with large granular eosinophilic cytoplasmic inclusion bodies and a small, peripherally displaced nucleus.

Management

Treatment is often unnecessary as lesions typically resolve on their own within six to twelve months. However, treatment may be pursued for cosmetic reasons or to prevent the spread of the virus, especially in the genital area. Options include:

• Topical Medications: Over-the-counter potassium hydroxide may offer modest benefits. Other topical agents like salicylic acid, benzoyl peroxide, and tretinoin have limited evidence of efficacy.
• Cimetidine and Podophyllotoxin: These medications can be used, but there is limited high-quality evidence supporting their effectiveness.
• Berdazimer Sodium: Recently approved in the United States for treating MC, this nitric oxide releasing agent is a new addition to the treatment arsenal.

• Surgical Options: Cryosurgery and curette scraping are effective but can be painful and may lead to scarring.
• Laser Therapy: Pulsed dye laser therapy is generally well tolerated and effective, but it is not widely evidenced for treating genital lesions.

Prognosis

MC typically resolves naturally within two years, usually within nine months. The lesions are only contagious while present, and once resolved, the virus does not remain dormant in the body as seen with herpesviruses. Thus, the infection will not reappear unless re-infected.

Epidemiology

As of 2010, approximately 122 million people globally (1.8% of the population) were affected by MC, with a higher prevalence in children aged one to ten years.

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Self-assessment MCQs (single best answer)

What causes Molluscum Contagiosum (MC)?

What is the typical appearance of MC lesions?

How is MC most commonly transmitted?

In which age group is MC most prevalent?

What histological feature is characteristic of MC?

Which of the following treatments is a newly approved option for MC in the United States?

What is a common complication of scratching MC lesions?

What is the average time frame for spontaneous resolution of MC lesions?

Which of the following is not a recommended treatment option for MC?

What percentage of the global population was affected by MC as of 2010?