11th August 2020

An 11-year-old boy is accompanied by his father to Accident & Emergency (A&E) after he developed red coloured urine

An 11-year-old boy is accompanied by his father to Accident & Emergency (A&E) after he developed red coloured urine. On taking a history, you note that the child has been generally well but has been complaining of an increasing feeling of lethargy in the past two weeks (not participating in sports at school) and has had some occasional episodes of abdominal pain, for which the parents mentioned no obvious triggers. There is no family history or social history of note and the child seems generally well in himself and is actively communicating and engaging with everyone. On physical examination of the child, you notice mild abdominal tenderness throughout the abdomen on light and deep palpation, and a purpuric, non-blanching raised erythematous rash on the buttocks and on the upper parts of the calves. You suspect a diagnosis and order a series of investigations and advise the parents and the child appropriately.

What is the most likely differential diagnosis causing the purpuric skin changes in this 11-year-old boy?

Select the SINGLE most appropriate option from the list below. Select ONE option only.