原句结构不变：Essential thrombocythemia（ET）的临床表现可能与早期/纤维化前原发性骨髓纤维化（pre-PMF）非常相似，特别是在表现为血小板增多（pre-PMF-T）的pre-PMF中，但可能与不同的结果相关。区分这两个实体非常重要。本研究的目的是解决区分pre-PMF-T和ET的临床和预后相关性。所有患者，包括258例ET和105例pre-PMF-T，均接受了JAK2V617F、MPL (exon 10)和CALR (exon 9)突变分析和JAK2V617F和CALR突变体等位基因负荷测试。与ET患者相比，pre-PMF-T患者年龄较大、白细胞和血小板计数较高，但血红蛋白水平较低。pre-PMF-T患者的总体、无白血病和无血栓生存期较ET患者短。ET患者的脑缺血性卒中率较高，而pre-PMF-T患者倾向于具有内脏静脉血栓性。JAK2V617F、CALR和MPL突变及CALR等位基因负荷的频率没有区别，但JAK2V617F突变体等位基因负荷在pre-PMF-T中明显高于ET。具有JAK2V617F突变的pre-PMF-T患者总体生存期和无血栓期较差，而驱动基因突变的状态未影响ET患者的结果。ET和pre-PMF-T是两个不同的疾病实体，具有不同的临床表型、基因型和结果。© The Author(s) 2023. Published by Oxford University Press on behalf of American Society for Clinical Pathology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

The clinical presentations of essential thrombocythemia (ET) may be quite similar to early/prefibrotic primary myelofibrosis (pre-PMF), especially in pre-PMF presenting with thrombocytosis (pre-PMF-T), but may be associated with a different outcome. It is very important to distinguish these two entities. The aim of this study was to address the clinical and prognostic relevance of distinguishing pre-PMF-T from ET.All patients, including 258 with ET and 105 with pre-PMF-T, received JAK2V617F, MPL (exon 10), and CALR (exon 9) mutation analysis and allele burden measurement for JAK2V617F and CALR mutants.Patients with pre-PMF-T had an older age and higher leukocyte and platelet counts but lower hemoglobin levels than patients with ET. Patients with pre-PMF-T had a shorter overall, leukemia-free, and thrombosis-free survival compared with patients with ET. Patients with ET had a higher rate of cerebral ischemic stroke, whereas patients with pre-PMF-T tended to have splanchnic vein thrombosis. The frequencies of JAK2V617F, CALR, and MPL mutations and CALR allele burden were no different, but JAK2V617F allele burden was significantly higher in pre-PMF-T. Patients with pre-PMF-T with the JAK2V617F mutation had an inferior overall survival and thrombosis-free survival, whereas the status of driver gene mutations did not influence the outcomes of patients with ET.ET and pre-PMF-T were two distinct disease entities and exhibited different clinical phenotype, genotype, and outcomes.© The Author(s) 2023. Published by Oxford University Press on behalf of American Society for Clinical Pathology. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.