Purpura describes bleeding into the skin from small blood vessels that produces a non-blanching rash. Smaller petechiae (1-2 mm in diameter) may also be seen. It is typically caused by low platelets but may also be seen with bleeding disorders, such as von Willebrand disease.
Purpuric rash secondary to medication-induced vasculitis. Image sourced from Wikipedia
It is important to recognise purpura as it can indicate the presence of serious underlying disease. Children with a new purpuric rash should be admitted immediately for investigations as it may be a sign of meningococcal septicaemia or acute lymphoblastic leukaemia. Parenteral antibiotics should be given prior to transfer if meningococcal septicaemia is suspected.
| Children | Adults |
|---|---|
| • Meningococcal septicaemia | |
| • Acute lymphoblastic leukaemia | |
| • Congenital bleeding disorders | |
| • Immune thrombocytopenic purpura | |
| • Henoch-Schonlein purpura | |
| • Non-accidental injury | • Immune thrombocytopenic purpura |
| • Bone marrow failure (secondary to leukaemias, myelodysplasia or bone metastases) | |
| • Senile purpura | |
| • Drugs (quinine, antiepileptics, antithrombotics) | |
| • Nutritional deficiencies (vitamins B12, C and folate) |
Raised superior vena cava pressure (e.g. secondary to a bad cough) may cause petechiae in the upper body but would not cause purpura.