Skin, vesicular rash

Question 1

Probability diagnosis

Answer 1

• Herpes simplex
• Herpes zoster
• Varicella (chicken pox)
• Hand, foot and mouth disease
• Dermatitis: contact, atopic
• Insect and arachnoid bites
• Molluscum contagiosum
• Burns

Question 2

Serious disorders not to be missed

Answer 2

Vascular:

• Allergic vasculitis

Infection:

• Bullous impetigo (scalded skin syndrome)
• Scabies
• Anthrax

Cancer:

• Associated e.g. lymphoma, leukaemia

Other:

• Erythema multiforme

Question 3

Pitfalls (often missed)

Answer 3

• Pompholyx
• Pemphigus/pemphigoid
• Dermatitis herpetiformis
• Fixed drug eruption e.g. sulphonamides
• Trauma e.g. skin friction, thermal, acid, caustic
• Rarities:
• Porphyria cutanea tarda
• Epidermolysis bullosa acquisita

Question 4

Masquerades checklist

Answer 4

Drugs e.g. penicillamine, barbiturates

Question 5

Key history

Answer 5

recent and general health esp. any infections

associated symptoms of infectious diseases.

any recent travel history

history of skin trauma

bites or stings

drug intake esp. antibiotics.

family history of bullous disorders

Question 6

Key examination

Answer 6

General examination of skin and mucus membranes including: mouth looking for hand, foot and mouth infection and pompholyx.

Question 7

Key investigations

Answer 7

Unlikely to be helpful.

Consider:

1. FBE
2. wound swabs (if evidence infection)
3. viral studies and patch testing