Background/Objectives: Overt primary myelofibrosis (PMF), secondary post-polycythemia vera (post-PV), and post-essential thrombocythemia (post-ET) myelofibrosis (SMF) are chronic myeloproliferative neoplasms (MPN) that sometimes present with extreme thrombocytosis (ExTh, platelet count > 1000 × 109/L), a phenomenon of uncertain clinical significance since there are no published data available.Methods: We retrospectively investigated the clinical correlations and associated outcomes of ExTh in a cohort of 172 patients with overt myelofibrosis diagnosed in six Croatian hematology centers.Results: ExTh was present in 5.8% of patients and was associated with post-ET etiology of myelofibrosis, older age, smaller spleen size, and the presence of arterial hypertension (p< 0.05 for all analyses). No significant associations were observed with sex, degree of bone marrow fibrosis, or driver mutation status. Over the follow-up period, patients with ExTh experienced a favorable course regarding survival (p< 0.001) and bleeding risk (p= 0.034), whereas no significant association with thrombotic risk was observed (p= 0.682).Conclusions: In contrast to its context in ET, ExTh in overt fibrotic MPN does not appear to confer higher bleeding or thrombotic risk. Instead, it is associated with more favorable survival outcomes and reduced bleeding risk.
背景/目的：显性原发性骨髓纤维化（PMF）、继发性真性红细胞增多症后（post-PV）及原发性血小板增多症后（post-ET）骨髓纤维化（SMF）属于慢性骨髓增殖性肿瘤（MPN），部分病例可表现为极度血小板增多（ExTh，血小板计数>1000×10⁹/L），由于缺乏公开数据，该现象的临床意义尚不明确。方法：我们回顾性分析了克罗地亚六家血液学中心确诊的172例显性骨髓纤维化患者队列，探究ExTh的临床相关性及其预后影响。结果：5.8%的患者存在ExTh，该现象与骨髓纤维化的post-ET病因、高龄、脾脏体积较小及合并动脉高血压显著相关（所有分析p<0.05）。未发现其与性别、骨髓纤维化程度或驱动基因突变状态存在显著关联。随访期间，ExTh患者在生存预后（p<0.001）和出血风险（p=0.034）方面呈现更优临床进程，而与血栓风险无显著相关性（p=0.682）。结论：与ET背景下的ExTh不同，显性纤维化MPN中的ExTh并未增加出血或血栓风险，反而与更良好的生存预后及更低的出血风险相关。
Extreme Thrombocytosis in Patients with Overt Myelofibrosis and Its Clinical Associations
肿瘤(癌症)患者之家