Overview
Molluscum contagiosum is a self-limiting viral skin infection caused by the molluscum contagiosum virus, a poxvirus. It may sometimes involve the eye.
Pathophysiology
It is transmitted via direct contact, autoinoculation, or via contaminated fomites. Upon entering the skin, the virus replicates and causes hyperplasia of infected cells, resulting in flesh-coloured, umbilicated papules.
Epidemiology
- Molluscum contagiosum is common in children
Risk Factors
- Close contact with an infected person
- Impaired skin barrier function – such as atopic dermatitis
- Immunocompromised states – such as HIV and immunosuppressive drugs
- Warmer climates
- Swimming
Presentation
Features of molluscum contagiosum are:
- Small, firm, umbilicated papules – found in clusters across the body, commonly the trunk, flexures, and genital areas in adults
- They tend to appear fleshy or pearly white
- Rarely, the eyelids may be affected
Management
Its diagnosis is clinical and, in most people, reassurance is sufficient as it is self-limiting and exclusion is not necessary.
However, in some circumstances, a referral to secondary care may be indicated:
- HIV + extensive lesions – urgently refer to an HIV specialist
- Eyelid/ocular lesions + red eye – urgently refer to ophthalmology
- Anogenital lesions – refer to genitourinary medicine for sexually transmitted infection screening
Complications
Pruritus and eczema – may be seen in 3/10 people and are more common in people with atopic dermatitis. Resolution may take longer in people with atopic dermatitis.
Hypersensitivity – in around 1/10 people, lesions may be surrounded by a halo of eczema (molluscum dermatitis) due to a hypersensitivity reaction and may result in an altered lesion appearance or abscess.
Scarring – may be seen in around 7% of people, rarely permanent.
Bacterial superinfection – repeated scratching can increase the risk of this and can lead to impetigo, cellulitis, folliculitis etc.
Ophthalmic complications – eye lesions can shed viral toxins into the eye and can cause conjunctivitis and corneal involvement.
Prognosis
- Molluscum contagiosum is benign, usually self-limiting, and often resolves within 18 months
- Resolution tends to take longer in people with coexisting atopic dermatitis and people with immunosuppression
