In the 2016 revised classification of myeloproliferative neoplasms pre-fibrotic primary myelofibrosis (pre-PMF) was recognized as a separate entity, distinct from essential thrombocythemia (ET). Owing that the majority of cases falling in the pre-PMF category were previously diagnosed as ET, one may question about the need to re-evaluate the results of epidemiologic, clinical, and molecular studies, and the results of clinical trials in the two entities. Based on a critical review of recently published studies, pre-PMF usually presents with a distinct clinical and hematological presentation and higher frequency of constitutional symptoms. JAK2V617F and CALR mutations in pre-PMF patients are superimposable to ET, whereas non-driver high-risk mutations are enriched in pre-PMF compared with ET. Thrombosis is not significantly different, whereas bleeding is more frequent in pre-PMF. Median survival is significantly shorter in pre-PMF and 10-year cumulative rates progression to overt myelofibrosis is 0-1% vs. 10-12%, and leukemic transformation is 1-2% vs. 2-6%, in ET and pre-fibrotic-PMF, respectively. Most patients fall in the lower prognostic IPSS group in which observation alone can be recommended. Patients at intermediate risk may require a symptom-driven treatment for anemia, splenomegaly or constitutional symptoms while cytoreductive drugs are indicated in the high-risk category.

中文翻译：

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世卫组织针对原发性血小板增多症的新分类要求修订现有证据。

在2016年修订的骨髓增生性肿瘤分类中，纤维化前原发性骨髓纤维化（pre-PMF）被认为是独立的实体，与原发性血小板增多症（ET）不同。由于大多数属于PMF前类别的病例先前都被诊断为ET，因此有人可能会质疑是否需要重新评估流行病学，临床和分子研究的结果以及这两个实体的临床试验结果。基于对近期发表的研究的严格评论，PMF前通常表现出明显的临床和血液学表现，且出现体质症状的频率更高。PMF前患者中的JAK2V617F和CALR突变可叠加至ET，而与ET相比，PMF前患者中的非驾驶员高风险突变更为丰富。血栓形成没有显着差异，而在PMF前出血更为频繁。PMF前和ET前的中位生存期显着缩短，并且10年累计发生率明显的骨髓纤维化的进展为0-1％比10-12％，白血病转化为1-2％对2-6％。 -fibrotic-PMF。大多数患者属于预后较低的IPSS组，建议单独观察。中度风险患者可能需要针对贫血，脾肿大或体质症状的症状驱动治疗，而高风险类别则应使用减细胞药物。大多数患者属于预后较低的IPSS组，建议单独观察。中度风险患者可能需要针对贫血，脾肿大或体质症状的症状驱动治疗，而高风险类别则应使用减细胞药物。大多数患者属于预后较低的IPSS组，建议单独观察。中度风险患者可能需要针对贫血，脾肿大或体质症状的症状驱动治疗，而高风险类别则应使用减细胞药物。