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Platelet diameters in inherited thrombocytopenias: analysis of 376 patients with all known disorders

Patrizia Noris, Ginevra Biino, Alessandro Pecci, Elisa Civaschi, Anna Savoia, Marco Seri, Federica Melazzini, Giuseppe Loffredo, Giovanna Russo, Valeria Bozzi, Lucia Dora Notarangelo, Paolo Gresele, Paula G. Heller, Nuria Pujol-Moix, Shinji Kunishima, Marco Cattaneo, James Bussel, Erica De Candia, Claudia Cagioni, Ugo Ramenghi, Serena Barozzi, Fabrizio Fabris and Carlo L. Balduini

Key Points

  • Measurement of platelet diameters in 376 patients resulted in a new classification of inherited thrombocytopenias based on platelet size.

  • Measurement of platelet diameters is a useful tool for differential diagnosis of inherited thrombocytopenias.

Abstract

Abnormalities of platelet size are one of the distinguishing features of inherited thrombocytopenias (ITs), and evaluation of blood films is recommended as an essential step for differential diagnosis of these disorders. Nevertheless, what we presently know about this subject is derived mainly from anecdotal evidence. To improve knowledge in this field, we evaluated platelet size on blood films obtained from 376 patients with all 19 forms of IT identified so far and found that these conditions differ not only in mean platelet diameter, but also in platelet diameter distribution width and the percentage of platelets with increased or reduced diameters. On the basis of these findings, we propose a new classification of ITs according to platelet size. It distinguishes forms with giant platelets, with large platelets, with normal or slightly increased platelet size, and with normal or slightly decreased platelet size. We also measured platelet diameters in 87 patients with immune thrombocytopenia and identified cutoff values for mean platelet diameter and the percentage of platelets with increased or reduced size that have good diagnostic accuracy in differentiating ITs with giant platelets and with normal or slightly decreased platelet size from immune thrombocytopenia and all other forms of IT.

  • Submitted March 21, 2014.
  • Accepted June 24, 2014.
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