Non blanching rashes in children

Non-blanching rashes are rashes which do not disappear with pressure, particularly using the ‘glass test’.

Most children with a non-blanching rash who are well will not have a serious underlying cause. In many cases, a simple viral illness (often adenovirus) is the final diagnosis. Other differentials include Henoch-Schonlein purpura (HSP), immune thrombocytopenic purpura (ITP) or mechanical causes including physical abuse.

However, for a small number of children, a non-blanching rash can indicate a more significant underlying cause such as meningococcal sepsis or haematological malignancy.

It therefore is important to assess all children with a non-blanching rash promptly to enable early diagnosis and treatment. All children with a non-blanching rash with or without fever require same-day assessment by the paediatric team in hospital unless there is a clear, accidental mechanical cause.

Non-blanching rashes occur from bleeding from small blood vessels in to the skin or mucosa. Petechiae are non-blanching pinpoint spots which are less than 3mm in diameter.

Purpura are non-blanching, greater than 3mm in diameter, and are sometimes palpable.

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