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

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.Fil: Noris, Patrizia. University of Pavia; ItaliaFil: Biino, Ginevra. Consiglio Nazionale Delle Ricerche. Istituto di Genetica Molecolare; ItaliaFil: Pecci, Alessandro. University of Pavia; ItaliaFil: Civaschi, Elisa. University of Pavia; ItaliaFil: Savoia, Anna. Università degli Studi di Trieste; Italia. Istituto Di Ricovero e Cura a Carattere Scientifico Burlo Garofolo; ItaliaFil: Seri, Marco. Università di Bologna; ItaliaFil: Melazzini, Federica. University of Pavia; ItaliaFil: Loffreddo, Giuseppe. Pausilipon Hospital; ItaliaFil: Russo, Giovana. Università degli Studi di Catania; ItaliaFil: Bozzi, Valeria. University of Pavia; ItaliaFil: Notarangelo, Lucia Dora. Spedali Civili. Ospedale dei Bambini; ItaliaFil: Gresele, Paolo. Università di Perugia; ItaliaFil: Heller, Paula Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Médicas. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Médicas; ArgentinaFil: Pujol Moix, Nuria. Universitat Autònoma de Barcelona; EspañaFil: Kunishima, Shinji. National Hospital Organization Nagoya Medical Center; JapónFil: Cattaneo, Marco. Università degli Studi di Milano; ItaliaFil: Bussel, James. Cornell University; Estados UnidosFil: de Candia, Erica. Universita Cattolica del Sacro Cuore; ItaliaFil: Cagioni, Claudia. University of Pavia; ItaliaFil: Ramenghi, Ugo. Università di Torino; ItaliaFil: Barozzi, Serena. University of Pavia; ItaliaFil: Fabris, Fabrizio. Università di Padova; ItaliaFil: Balduini, Carlo L.. University of Pavia; Itali