Thrombotic thrombocytopenic purpura in a patient with adult-onset Still's disease: report of a rare entity.

Adult-onset Still's disease (AOSD) is a rare, systemic inflammatory disorder characterised by daily fever, arthritis, a salmon-pink rash and leucocytosis. Thrombotic thrombocytopenic purpura (TTP) is included in the class of thrombotic microangiopathies and manifests clinically as microangiopathic haemolytic anaemia (MAHA), thrombocytopenia and ischaemic tissue injury secondary to microthrombi. TTP is caused by either an autoimmune, congenital or idiopathic deficiency of ADAMTS13 and carries a high mortality rate. TTP can be seen in patients diagnosed with other rheumatologic conditions, with systemic lupus erythematosus being the most common, but is rarely seen in AOSD. Permanent complication rates from TTP in the setting of AOSD have been reported to be >50%. This case study aims to report one of the rare instances of TTP presenting in a patient with known AOSD to broaden the knowledge base regarding these rare coexisting pathologies.