A diagnostic approach that may help to discriminate inherited thrombocytopenia from chronic immune thrombocytopenia in adult patients

Inherited thrombocytopenia (IT) is a heterogeneous group of rare diseases that are often confused with immune thrombocytopenia (ITP). The objective of this study was to supply clinicobiological elements that allow a distinction to be drawn between IT and chronic ITP. We then compared 23 adult patients with IT and 9 patients with chronic ITP. Our study revealed six discriminating criteria: (i) an age of discovery 11 fL: PPV = 93.3% [68.1; 99.8], (v) an excess of giant platelets on blood smear: 100.0% [76.8; 100.0], and (vi) a percentage >44% of platelets with a surface area >4 µm2 in electron microscopy: PPV = 83.3% [58.6; 96.4]. If at least three of these criteria were combined, it was possible to distinguish IT from chronic ITP with 91.3% [72.0; 98.9] sensitivity and PPV = 100.0% [66.4; 100.0] specificity. The secondary objective of this study was to assess the prevalence of potential IT diagnosis in patients with chronic thrombocytopenia of uncertain origin. Applying our diagnostic approach to a series of 20 cases allowed us to estimate that 40% of them could be suffering from IT. Finally, our diagnostic approach may help to correctly distinguish IT from chronic ITP, particularly in the context of macrothrombocytopenia.遗传性血小板减少症（Inherited thrombocytopenia, IT）是一类异质性罕见疾病，常与免疫性血小板减少症（immune thrombocytopenia, ITP）混淆。本研究旨在明确可用于区分IT与慢性ITP的临床生物学特征。本研究共纳入23例IT成人患者与9例慢性ITP患者开展对照分析。结果显示六项鉴别诊断标准：（i）确诊时相关的11飞升（fL）：阳性预测值（Positive Predictive Value, PPV）=93.3%[68.1; 99.8]；（v）血涂片可见巨大血小板增多：100.0%[76.8; 100.0]；（vi）电子显微镜下表面积＞4μm²的血小板占比＞44%：PPV=83.3%[58.6; 96.4]。若同时满足至少三项上述标准，则可区分IT与慢性ITP，此时灵敏度为91.3%[72.0; 98.9]，PPV=100.0%[66.4; 100.0]。本研究的次要目标为评估不明原因慢性血小板减少症患者中潜在IT诊断的患病率。将本诊断方法应用于20例患者队列后，估算其中40%可能罹患IT。最后，本研究提出的诊断方法可有效区分IT与慢性ITP，尤其适用于巨血小板减少症场景。