A rare cause of shock in cases of refractory hypotension, hypoproteinaemia and haemoconcentration.

This case report describes a woman in her mid-40s of European ancestry presenting with recurrent profound hypotension, hypoproteinaemia and haemoconcentration. She first presented following administration of a Japanese encephalitis vaccine. The initial differential diagnoses included sepsis or an anaphylactic reaction to the vaccine. No evidence of allergy or infection was found during extensive investigation including a lumbar puncture. Following a second similar presentation, she was diagnosed with idiopathic systemic capillary leak syndrome (ISCLS). Her presentation was highly atypical due to the high frequency of episodes encountered (34 over a near 6-year period). A variety of triggers for episodes were identified including COVID-19 infections, influenza infection and vaccinations. We discuss her clinical presentation, investigations, ISCLS episode triggers and management. This highlights the benefits of intravenous immunoglobulins (IVIg), both for prophylaxis and for the acute treatment of ISCLS episodes.