molluscum contagiosum

Question 1

definition of molluscum contagiosum

Answer 1

common childhood skin infection with multiple translucent vesicle papules that have a depressed central punctum

caused by contact transmissible pox virus

in adults - suspect HIV - widespread and unusual sites, face, genitals

Question 2

aetiology of molluscum contagiosum

Answer 2

lesions caused by the molluscum contagiosum virus (MCV) - 3 types:

1. MCV 1 and 1v - seen in children - child-child contact or fomites
2. MCV 2 - sexually transmitted virus in the groin of adults and generalised immunocompromised people
3. MCV 3 - rare subtype in any age

all caused by MCV poxvirus - largest known virus

the virus infects keratinocytes and mucosa = papular lesions

Question 3

pathology of molluscum contagiosum

Answer 3

MCV infects the skin = lesion appearance within a few days to up to 6weeks later

virus = abnormal keratinocyte growth and the appearance of heavily stained cells on haematoxylin and eosin staining

abnormal keratinocytes are termed henderson-patterson bodies

doesnt cause dysplastic lesions

natural course of infection - spontaneous clearance in 2-4yrs in the immunocompetent with more prolonged illness in the immunocomp

Clearance requires the appearance of anti-molluscum antibodies and cellular immunity.

MCV encodes virulence factors that prevent the natural immune process from effectively clearuing the lesions

MCV also encodes a glutathione peroxidase, which protects infected cells from oxidative damage by peroxides.

Question 4

epidemiology of molluscum contagiosum

Answer 4

mostly affects children

overall prevalence in children estimated 5% - 12%.

adults can be infected by sexual transmission

Question 5

signs and sx of molluscum contagiosum

Answer 5

pearly papule with central dell - >50lesions may imply immunosuppresion

surrounding erythema

facial or groin distribution of lesions

pruritus

atopic dematitis

Question 6

Ix for molluscum contagiosum

Answer 6

curettage biopsy - rarely needed, ay be needed in children to distinguish genital condyloma.

Tzanck stain - purple ovoid keratinocytes

haematoxylin and eosin staining - performed on biopsy and provides a definite dx - Henderson-Patterson bodies

HIV test of refractory or extensive disease

Question 7

classification of molluscum lesions

Answer 7

molluscum contagiosum - common molluscum that are pearly papules, with central dell over the chest wall and axillae in children, and groin and inner thigh in adults

giant molluscum - lesions are smooth papules or nodules w/o entral dell and are present in the inter-gluteal area or on sole of foot

inflammed molluscum - manifest erythema, swelling, pruritus - marker of immune response to the lesions