An 8 month girl is brought to the Emergency Department by her parents. She has not been eating as much as usual over the previous 24 hours and has now decreased her fluid intake. She has had a fever of 38 and they are very concerned about this rash she has over her legs. It was also originally over her arms, but that is improving.
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Rashes can be scary. Rashes in children can be scarier.
So let’s look at this rash and see what we can come up with.

On examination the child was alert well, with no other findings except a temperature. The rash was a blanching confluent rash, with some areas that looked like target lesions.

Diagnosis?

Erythema Multiforme.
Also called mucocutaneous hypersensitivity reaction. It is characterised by only one mucosal surface being involved. The lesions are usually macules or papules that expand and evolve into target lesions.

Aetiology
Some 50% of cases are idiopathic. In children it is usually caused by an infection (viral or bacterial) and in adults, it is usually a drug reaction.

It can also occur secondary to malignancy, pregnancy, post vaccination, or a number of other causes.

Viral causes include herpes simplex, EBV and varicella.
Bacterial causes include mycoplasma pneumonia.
Drugs that may cause the reaction include sulfonamides, NSAIDs, antibiotics and phenytoin.

How to Manage
To do investigations are necessary. Treat the cause i.e. remove the drug etc. and give symptomatic relief. No systemic steroids in mild cases.

In this case, the child was admitted and observed.