Clinical Case 032: making rash decisions….

This girl has a history of a few days of fever, cough and irritability.  She has in the past 24 hours developed this impressive rash that covers her face, arms and legs.  The lesions are slightly raised and blanch easily.  They are not particularly itchy.  This is a spot diagnosis:












Pattern recognition is key in this scenario – it can make the difference between a quick, confident diagnosis with appropriate reassurance and a prolonged, stressful and often unnecessary series of investigations.


This is erythema multiforme. Here is a neat review from AFP in 2008

HSV – herpes labialis, or primary herpes gingivostomatitis

Mycoplasma pneumonia

Drugs: anticonvulsants, sulfurs, NSAIDs, penicillins, anti-retrovirals

Simple EM requires no treatment and is self-limiting, a careful history and exam to look for a cause is all you need.

There is the smallest chance that the child may develop Stevens-Johnson syndrome or toxic epidermal necrolysis [though some expers feel they are not the same disease].  I tend to opt for reassurance – as the most likely outcome is benign, annoying rash which goes away – “but return if worse”.

This rash can take a month or more to disappear – so warn the parents. And it can recur – repeatedly.


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