Viral exanthema (I)

Question 1

Summary - what are some common terms used to describe skin lesions?

Answer 1

• macule - flat area <1cm
• patch - large macule >1cm
• papule - raised area <1cm
• nodule - larger papule >1cm
• vesicle - small fluid-filled lesion <0.5cm
• bulla - larger vesicle >0.5cm
• pustule - pus-filled lesion
• wheal - transient raised papule/plaque caused by dermal oedema
• scale - flakes of stratum corneum
• crust - dried serum, blood or purulent exudate on skin
• erosion - loss of epidermis, heal without scarring
• ulcer - loss of epidermis and dermis, heals with scarring
• excoriation - loss of epidermis following trauma
• fissure - split in the skin
• lichenification - thickening of skin with accentuation of skin markings
• purpura - area of colour change due to bleeding into skin, does not blanch on pressure
• petechiae - pinpoint purpuric lesion
• ecchymosis - larger area of purpura

Question 2

Define viral exanthema.

Answer 2

Widespread skin rash accompanying a viral illness

Question 3

Which diseases is viral exanthema commonly associated with? (3)

Answer 3

Very common in childhood - especially:

• chickenpox (VZV)
• measles (morbillivirus)
• rubella

Question 4

What has helped reduce the prevalence of diseases causing viral exanthema?

Answer 4

Immunisations have decreased number of MMR and chickenpox cases

Question 5

What are the clinical features of viral exanthema? (8)

Answer 5

• spots/blotches on skin with widespread rash - most commonly seen on trunk
• fever
• malaise
• headache
• loss of appetite
• muscular aches and pains
• abdominal pain
• irritability

Question 6

What investigations would you do for viral exanthema? (2)

Answer 6

• viral swab - viral culture, immunofluorescence and PCR
• blood tests - serology, PCR, RNA/DNA, ANA, tissue antibodies
• (genotyping)

Question 7

What are some differential diagnoses for viral exanthema? (8)

Answer 7

• varicella zoster virus (chickenpox) - erythematous, vesicular, crusting + pruritus
• morbillivirus (measles) - erythematous, confluent, maculopapular + Koplik spots + conjunctivitis
• rubivirus (rubella) - pink, maculopapular + Forchheimer spots
• parvovirus B19 (erythema infectiosum) - slapped cheek appearance + aplastic crisis
• Streptococcus pyogenes (Scarlet fever) - erythema with sandpaper-like texture + strawberry tongue + rheumatic fever
• Coxsackie A virus (hand-foot-and-mouth disease) - elliptical vesicles, erythematous, oral, erosions
• pityriasis rosea (HSV 6/7) - pink, maculopapular
• eczema herpeticum (HSV 1/2) - monomorphic punched-out erosions + flu-like Sx

Question 8

How do we manage fever in viral exanthema?

Answer 8

Antipyretics - paracetamol

Question 9

What do we give to reduce itching/pruritus in viral exanthema?

Answer 9

Moisturising emollients