[Thrombocytopenic thrombotic purpura. Retrospective study of 22 consecutive occurrences in 16 patients]

Thrombotic Thrombocytopenic Purpura (TTP) is an uncommon clinical syndrome with high mortality rate in the absence of treatment. Despite the therapeutic efficacy of plasma exchange, patients often relapse even after long periods of time in remission. Over the last few years, late relapses in previously diagnosed patients have been seen in our hospital.

We analyzed retrospectively 22 episodes of TTP in 16 patients diagnosed during a four-year period. We reviewed the clinical features at diagnosis as well as the therapeutic results. In all but one, the treatment included daily plasma exchange. Other treatments, including vincristine, were also used in addition to plasma exchange, in 18 of 21 episodes.

A complete remission was obtained in eighty-two percent of the episodes treated by plasma exchange. The median number of plasma exchange to achieve a complete remission was 6. In 4 episodes, 20 or more plasma exchange were required before achieving a satisfactory response. A complete remission was obtained in 78% of episodes where vincristine was used, versus 84% response rate in episodes where vincristine was not used. In four patients the cause death was directly related to TTP, while a fifth patients died of progressive lymphoma without evidence of TTP. Five of the eleven surviving patients relapsed with a median time to relapse of 24.6 months. Relapsing episodes presented with a less severe clinical picture including less clear signs of microangiopathic hemolytic anemia (MAHA), when compared with the initial ones. All patients in relapse responded promptly to treatment. The variables analyzed failed to predict either the response to treatment or the probability of relapse.

The therapeutic efficacy of plasma exchange in the treatment of TTP has been demonstrated in our series as previously observed by many other groups. We have observed some slow responders where the prolongation of treatment by plasma exchange succeeded in achieving a complete remission. The use of vincristine did not show any therapeutical advantage in our experience.