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Why has this snuffly toddler got a rash on his legs and arms?


The patient

It was the end of surgery – and just a few ‘extras' between me and a well earned cup of coffee. First up was a snuffly toddler. ‘It's not his cold I'm worried about,' explained his mum, pulling off his clothes. ‘It's these weird spots.' She revealed a florid rash mainly on his legs, with some on his arms, too. Otherwise he seemed fine, was on no regular medication and had no past medical history of note. For his upper respiratory tract infection, his mum had simply given him a few doses of paediatric ibuprofen.

First instinct

As the child looked fine, and the draw of caffeine was strong, I was largely working on auto-doc. I gave the spots a cursory examination – they well were defined and maculopapular, apparently coalescing in some places – and ensured that they blanched. The cop-out – and probably correct – diagnosis was of a non-specific viral rash. So that's what I opted for, although something was ringing bells in my head – which was why I told mum to return if the spots changed considerably, the child became ill or she was otherwise concerned.

Differential diagnosis

• Non-specific viral rash

• Urticaria

• Drug rash

• Henoch-Schonlein purpura

• Vasculitic rash.

We see non-specific viral rashes every day, of course – so purely from a statistical perspective, this was likely, and fitted with the concurrent URTI.

The rash also looked a bit urticarial in places, especially where it was coalescing. Urticaria would fit with the accompanying viral illness, or could have been a reaction to medication. In fact, given that the mum had treated the child with some doses of ibuprofen, a drug-related rash remained a strong possibility. One obscure differential was Henoch-Schonlein purpura. The distribution of the rash and the associated URTI were suggestive, but I dismissed the possibility on the basis that the rash certainly wasn't purpuric.

The slightly odd appearance and distribution did remind me of vasculitic rashes I'd seen before, though – so these remained on the differential list.

The hidden clue

All became much clearer the following day, when mum returned with an even spottier child. He remained reasonably well, though a bit grumpier than previously, and was apparently troubled by occasional abdominal pain.

But the most obvious change was with the rash. The distribution remained much the same, but there were now distinct petechial areas, which hadn't been present the previous day.

Getting on the right track

The duration of the history and the fact that the child remained well reassured me that this wasn't anything catastrophic like meningococcal septicaemia – and a platelet disorder seemed unlikely.

Henoch-Schonlein purpura, though, was now a front runner. In fact, it now seemed almost obvious that the child had a viral illness, now with abdominal pain and a suggestive rash. As ever, seeing the patient in the early stages of the illness had confused the issue – particularly given that, despite the name ‘Henoch-Schonlein purpura', the rash may not be purpuric at first.

We managed to obtain a urine specimen which revealed protein and blood – so the child was referred to hospital, where the diagnosis was confirmed.

Dr Keith Hopcroft is a GP in Laindon, Essex

HenochSchonlein Purpura HenochSchonlein Purpura


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