Hyperviscosity-related splenic infarction, gastrointestinal ischaemia-reperfusion injury and transient dysarthria in a patient with distributive shock due to idiopathic systemic capillary leak syndrome (Clarkson's syndrome).

Clarkson's syndrome, also known as idiopathic systemic capillary leak syndrome, is characterised by vascular hyperpermeability resulting in intravascular hypovolaemia and shock. A clinician should consider the diagnosis if other causes of shock, for example, sepsis and anaphylaxis, are ruled out and concomitant hyperviscosity is not caused by a myeloproliferative disease. Here, we describe a patient presenting with severe plasma leakage and assumable blood hyperviscosity leading to splenic infarction, gastrointestinal ischaemia-reperfusion syndrome and transient dysarthria. Our patient was first suspected of polycythaemia vera and phlebotomies were performed. Awareness of this syndrome and subsequent correct treatment is essential to prevent complications and to reduce mortality. As in our patient, most patients with Clarkson's syndrome have a monoclonal gammopathy, light-chain-type kappa. Prophylactic treatment with intravenous immunoglobulin (IVIg) is advised to prevent recurrence of capillary leak. Our patient did not suffer from another symptomatic episode after starting IVIg. © BMJ Publishing Group Limited 2020. No commercial re-use. See rights and permissions. Published by BMJ.