Molluscum contagiosum

Question 1

Define molluscum contagiosum.

Answer 1

Molluscum contagiosum is a common childhood skin infection.

They appear as pearl-like, smooth papules, which are umbilicated.

It is caused by a contact-transmissible pox virus, molluscum contagiosum virus. In adults, can be sexually transmited. In adults suspect HIV.

Question 2

How common is molluscum contagiosum?

Answer 2

• Most common in children - 5-12% prevalence
• Adults affected by sexual transmission
• More common in tropical climates

Question 3

What are the risk factors for molluscum contagiosum?

Answer 3

• Close contact with infected individual
• Sexual contact with infected individual
• HIV infection
• Tropical climate
• Swimming - more common in frequent swimmers

Question 4

What is the aetiology of molluscum contagiosum?

Answer 4

There are 3 types of molluscum contagiosum virus MCV1-3

• MCV 1 and 1v - in chilren due to contact or fomites
• MCV2 - sexually transmitted affecting groin or generalised in immunocompromised
• MCV3 - rare at any age

MCV is a poxvirus. Poxviruses are the largest known viruses. They infect the keratinocytes and mucosa –> papular lesions.

Question 5

What are the abnormal keratinocytes in MCV called?

Answer 5

Henderson-Patterson bodies - they are abnormal keratinocytes which are heavily stained with haematoxylin and eosin stain

Question 6

How quickly do molluscum contagiosum lesions appear and how quickly do they resolve?

Answer 6

Appear in a few days to 6 weeks after infection

Natural course of infection causes spontaneous clearance in 2-4 years (prolonged if immunocompromised) - molluscum antibodies and cellular immunity forms.

Question 7

What are the signs and symptoms of molluscum contagiosum?

Answer 7

• Pearly papule with a central dell
• Surrounding erythema - lesions may be excoriated and surrounded by dermatitis.
• Facial or groin distribution of lesions - these are not treated in children
• Pruritus
• Atopic dermatitis may coexist

Note:

In children lesions may be small enough to mimic milia, small cysts created by blockage of sweat glands. Ask about infected siblings.

Question 8

What investigations would you do for molluscum contagiosum?

Answer 8

99% clinically diagnosed

Other:

• Curettage biopsy can be used to confirm diagnosis in cases of suspected sexual abuse
• Inflammed molluscum can be tested for infection - culture for superinfection with flora similar to that seen in impetigo
• Assess for HIV if resistant or refractory disease