ABSTRACT
INTRODUCTION Thrombotic thrombocytopenic purpura (TTP) is a severe multisystem disorder characterized by low-grade fever, thrombocytopenia, microangiopathic hemolytic anemia (MAHA), fluctuating neurological symptoms and signs, and impaired renal function.1,2 TTP usually affects young people in previously good health. Its presentation is variable, but most patients seek medical attention for fluctuating neurological abnormalities or hemorrhagic manifestations. Other presenting symptoms include malaise and weakness, abdominal pain, nausea and vomiting, and fever. The median age at diagnosis is 35 years, but TTP has been reported in all age groups. The male to female ratio is 2:3.2-4
There are four possible clinical courses of TTP:
• single-episode TTP; • relapsing TTP; • chronic TTP; and • childhood or familial TTP.5-7
Although the majority of patients have only one episode of TTP, the higher survival rates resulting from new therapies has changed the course of the disease. About half of the patients now suffer from relapsing TTP, in which recurring episodes are separated by months or years of good health.3,7-9 The Canadian Apheresis Group reported that 17 of 63 TTP patients have had one or more recurrences, occurring 7 months to 8 years after the first episode. In all surviving patients the recurrence rate after 10 years was 36%.10 Bell reported on 206 of 319 (64%) patients with TTP and hemolytic-uremic syndrome who experienced a relapse.3 In 69% of these patients, the relapse occurred during the treatment period, while the others had a relapse 4-8 weeks after discontinuation of the plasma exchange therapy. The longest time interval between the first TTP episode and the relapse was 5 years. Of the 206 patients, 84% had only one episode of relapse while the others had between two and six relapses. Clinical deterioration was noted in only 3% of the patients. All other patients had only mild disease with some laboratory anomalies (mainly thrombocytopenia). In this study, no predicting factor for TTP relapse could be found.3 A rare subgroup of patients had chronic relapsing TTP, characterized by very frequent episodes with abnormally large multimers of von Willebrand factor (vWF) in their plasma during remissions.11 The childhood variant of TTP is even rarer and only a few cases have been reported.
