Rash

Question 1

Itchy rash causes

Answer 1

Eczema
* very common, often involves face, elbow and knee flexures

Eczema herpeticum
* Painful, ulcerations

Seborrhoeic dermatitis
* affects infants, often in association with cradle cap

Scabies
* itchy where mite has burrowed

Kawasaki
* morbilliform (measles-like), maculopapular (red patches and bumps), erythematous (red skin) or target-like and may be persistent over days or evanescent

Insect bites
* affects uncovered areas such as arms and legs

Drug allergy

Urticaria – idiopathic or secondary to allergens, consists of wheal (raised and white) and flare (red)

Fungal infections – e.g. tinea capitis or tinea pedis (athlete’s foot)

Chickenpox

Hand foot and mouth disease - vesicles

Nappy rash

Pityriasis rosea
* Tends to follow the line of the ribs posteriorly
* Usually begin with single round or oval scaly macule called herald patch

Toxic shock syndrome - diffuse erythematous macular

Dengue
* can be itchy sometimes
* Fine erythematous
* Blanching rash at first, turning into non-blanching

Scarlet fever
* Can be itchy
* Fine, punctate erythema (pinhead) -> first appears on torso and spares palms and soles
* Flushed cheeks, perioral sparing
* Desquamation layer in course of illness- particularly fingers + toes

Question 2

Painless rashes

Answer 2

1. Part of prodromal Hep B infection
2. Post-viral infection rash
3. EBV - maculopapular
4. HHV-6 and HHV-7 - maculopapular
5. Parvovirus B19 - slapcheek syndrome
6. Measles
   * Maculopapular rash- starts behind ears and face, then to whole body
7. Rubella
   * Maculopapular rash appear on the FACE and spreads centrifugally to cover the whole body
8. Syphilis
9. Meningitis - non-blanching purpuric
10. SLE - usually facial
11. Dermatomyositis - usually facial
12. HSP
    * Purpura over buttocks, lower limbs and elbows
    * Non-blanching
13. CMV - petechiae
14. Pertussis - petechiae
15. Idiopathic thrombocytopenia | - non-blanching
16. Listeria - widespread

Question 3

Erythema nodosum causes

Answer 3

Red or violet subcutaneous nodules located pretibially

1. Streptococcal infection
2. Primary TB
3. EBV
4. IBD
5. Drug reaction - sulphonamides, penicillin, COCP, Dapsone
6. Idiopathic
7. IBD
8. (Sarcoidosis- common in adults, rare in children)

Treatment: underlying cause, symptomatic with cool compresses and NSAIDs

Usually heal after several weeks

Question 4

Erythema multiform

Answer 4

Target-like lesions on skin which can progress to erosions of bullae

1. HSV
2. M. pneumoniae infection
3. Other infections
4. Drug reaction
5. SLE
6. IBD
7. Idiopathic

Answer 5

Answer 6