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Chapter 31 INHERITED THROMBOCYTOPENIAS
Blood film evaluation is is an an an important tool in in the diagnosis of inherited thrombocytopenias
(ITs) because many of of these forms present with specific and and easily recognizable morphological abnormalities of of platelets and and more rarely leukocytes and erythrocytes Thus microscope analysis of blood cells is is an an an an important step for generating one or or or or more diagnostic hypotheses and to guide the the the search for the the the corresponding genetic defect In cases in in which which massive sequencing is is performed first blood film analysis can can be of of significant help in in in deciding which which of of the often many variants that are identified has a a a a a a a a a a a a causative role Blood film evaluation is recommended also to distinguish ITs from immune thrombocytopenia (ITP) In fact the low platelet count of IT IT IT patients is is is sometimes recognized long after birth and these patients are misdiagnosed with ITP So recognition of of one or or more of of the the morphological defects that are typical of of ITs indicates an an IT IT IT instead of of an an ITP The most frequent morphological abnormality of platelets in ITs is is enlarged size (Noris et et al al al 2014) One mi- ght think that cell counter measurement of mean platelet volume represents a a a a a a a convenient alternative to blood film evaluation for for recognizing this this abnormality However this this is is is not true for for the many patients with very large platelets platelets because the the the electronic instruments do not usually recognize these elements as
platelets platelets and therefore underestimate both platelet platelet count count and mean platelet platelet volume Many cell counters can measure the distribution width of of platelet platelet volume and the the percentage of of enlarged platelets but even these measurements are not reliable in in cases of severe platelet macrocytosis for the reasons explained above Bone marrow examination is is only rarely required in in the diagnosis of ITs and as
a a a a a a a a a consequence we have little information on on on on on the the bone marrow profile in in these conditions Table 1 summarizes the morphological abnormalities of blood and bone marrow cells that are recognizable by optical microscope examination and that can be used for diagnostic purposes For further details on on ITs we refer to reviews that discuss these disorders in greater depth (Noris and Pecci Pecci 2017 Pecci Pecci et et al 2016 Savoia et et al 2016) References
Noris P P P Biino G Pecci A et et et al al al Platelet diameters in in in inherited thrombocytopenias: analysis of 376 pa ents with all known disorders Blood 2014 124(6):e4-e10 Noris P P P and Pecci A A Hereditary thrombocytopenias: a a a a a a a growing list of disorders Hematology Am Soc Hematol Hematol Educ Program 2017 2017 2017(1):385-399 Pecci A Diagnosis and treatment of inherited thrombocytopenias
Clin Genet 2016 89(2):141-153 Savoia A Molecular basis of inherited thrombocytopenias: an update Curr Opin Hematol 2016 23(5):486-492 237




























































































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