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Thrombocytopenia without excess of destruction : a misclassifield sundrome Volume 2, issue 3, Mai - Juin 1996

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Service de médecine nucléaire, hôpital Saint-Louis, 1, avenue Claude-Vellefaux, 75010 Paris.

The present review provides an analysis of the diagnostic criteria of ITP, underlines the clinical interest of the isotopic measurement of the platelet life span, and summarizes the causes of the chronic thrombocytopenias due to a platelet production defect. Most of the cases are constitutional thrombocytopenias, observed in children or young adults. The platelet count is generally 50-100.109/l, stable at the long term. A macrothrombocytosis is generally observed. The platelet in vitro function is normal, and so the absence of clinical haemorragic events. In most these cases, the bone marrow megakaryocytosis is normal, not increased as in ITP. The treatments generally used in ITP (corticosteroids, immunoglobulins, splenectomy) are always inefficient. When a genetic study was possible, an autosomal transmission was genrally observed. Unfortunately, we don't have yet a biochemical or molecular definition of this (or these) disease(s). In older patients (most of them more than 60), we observed acquired thrombocytopenias, without platelet macrocytosis, with a normal or decreased megakaryocytosis in the bone marrow. An associated granulocytopenia, or a red cell macrocytosis, or a bone marrow dysmyelopoiesis, may suggest a myelodysplastic disorder, which was proved in some cases by an evolution towards acute leukamia. But half of these patients have a long-term stable, and pure thrombocytopenia. These patients may be classified as the platelet equivalent of the refractory anemias described by the FAB group. These platelet defects are frequent and they deserve diagnosis - particularly when taking into account the risks, and the cost, of unuseful therapies.