We read with interest the article by Abidin and Jalaluddin1 They reported a 9-year-old boy who developed acute compartment syndrome of the left hand associated with Henoch–Schönlein purpura (HSP) after removal of the arterial cannulation.1 They speculated that spontaneous vasculitic bleeding might have caused the compartment syndrome.1 Compartment syndromes often develop during reperfusion following a period of ischaemia.2 Ischaemia causes a gradual depletion of intracellular stores of glycogen, and an increase both in glycolysis-related products (e.g. lactic acid) and intracellular reducing agents.2 Reperfusion may cause harmful effects by production of oxygen-free radicals, calcium influx and the sequestration of white blood cells in the muscle.2 Arterial cannulation itself can cause thrombosis and ischaemia, and HSP may also result in peripheral ischemia as a result of hypercoagulable tendency at the acute stage of the disease.3 Therefore, reperfusion injury after removal of the arterial cannulation might have been one of the important factors in the pathogenesis of compartment syndrome in Abidin and Jalaluddin's patient.1 Also, fasciotomy decompression was performed in this case which revealed findings of transudative fluid in the thenar compartment as well as haematomas in the hypothenar compartment.1 Wang et al.4 reported that soft tissue oedema was observed in 30% of the 50 patients with HSP, and Somekh et al.5 reported three children with HSP who developed severe symmetrical muscle pain in the legs, suggesting that intramuscular bleeding could be the underlying cause of their symptoms. Therefore, there is a possibility that intracompartmental volume might be increased by oedema and haemorrhage as a result of HSP itself in Abidin and Jalaluddin's patient.1 In conclusion, arterial cannulation should be avoided in children with HSP because of the risk of thrombogenic tendency, ischaemia, soft tissue oedema and intramuscular bleeding, all of which could lead to compartment syndrome. Further studies should be performed to identify the serum markers to predict the development of thrombosis or compartment syndrome in children with HSP.