The onset of thrombotic thrombocytopenic purpura (TTP) in a patient followed up for SLE is described. TTP is assigned to the thrombocytopenias with high turnover and peripheral platelet destruction. Aetiopathogenesis of TTP seems to be caused by structural alteration of vonWillebrand factor (vWF), resulting in the high multimers (ultra large–UL) presence. Treatment consists of vWF metalloproteinase administration by fresh frozen plasma or plasma exchange by plasmapheresis. The case of 35 years old woman with TTP followed up for SLE is described. She was admitted with haemolytic anaemia with later evolution of neurological symptoms and respiratory arrest due to pulmonary oedema necessitating ventilatory support and with manifestation of cardiac insufficiency. The presence of schistocytes, thrombocytopenia, fever, and neurological symptoms led to the diagnosis of TTP. Treatment using high doses of fresh frozen plasma or plasma exchange by plasmapheresiswasstartedandpromptimprovement of clinicalandlaboratory statuswasobserved. Elective splenectomy was performed for TTP relaps which resulted again in the improvement of blood count. TTP can occur as secondary syndrom in systemic connective tissue diseases or can originate in consequence of some drug treatment. It is necessary to think of the disease in case of decline of blood count in such conditions, since not recognized or inadequate treatment can lead to lethal outcome.

        Key words: SLE, thrombotic thrombocytopenic purpura