[Thrombotic thrombocytopenic purpura].

Thrombotic thrombocytopenic purpura (TTP) is an uncommon disorder which usually occurs in young adults. It is characterized by a pentad of clinical findings: fever, neurological abnormalities, renal dysfunction, microangiopathic hemolytic anemia and thrombocytopenia. The histological hallmark is the presence of platelet thrombi occluding the microcirculation of multiple organs. The etiology and pathogenesis of disseminated platelet aggregation are uncertain and obviously not uniform in individual patients. Experimental findings suggest that microthrombi may result from intravascular platelet activation or form secondarily at sites of vessel wall damage. The differential diagnosis of TTP includes the hemolytic uremic syndrome in which the microangiopathic changes are exclusively found in the kidneys. When untreated, TTP invariably runs a progressive and fatal course. In recent years, prognosis has been improved by new forms of therapy such as plasmapheresis or infusions of fresh frozen plasma which may lead to recovery in about 80% of patients.