A lively discussion persists regarding the diagnostic criteria for essential thrombocythemia (ET), primary myelofibrosis (PMF) and polycythemia vera (PV), particularly in relation to early/pre-fibrotic myelofibrosis (pre-PMF), a disease entity initially introduced in 2001 by the 3rd edition of the World Health Organization (WHO) classification. The definition and criteria used to diagnose pre-PMF have been progressively modified over time. The most update definition of pre-PMF can be found in the International Consensus Classification (ICC) published in 2022. An updated largely similar definition is also incorporated in the recently published 5th edition of WHO classification (2024). Diagnostic criteria for ET have undergone changes up to 2016/17 for the revised 4th edition of the WHO. In particular the threshold value for platelets were lowered and the important discrimination between “true” and “false” ET (in reality pre-PMF) been widely acknowledged. To avoid misdiagnose in early phase PV, the criteria for gender-adjusted thresholds for hemoglobin/ hematocrit have been lowered and the identification of an appropriate bone marrow (BM) morphology was upgraded as a major diagnostic criterion. Given the prominent role of morphology in MPN-related diagnostic algorithms, the diagnostic adequacy of the BM biopsy (sample procurement and proper laboratory handling) as emphasized in former WHO editions and in the ICC, was not addressed by the WHO 5th. The essential role of genetic markers is recognized by both classifications. A comparison between the revised 4th edition WHO classification and the ICC versus the WHO 5th reveals no significant differences, with the exception of the occurrence of leukoerythroblastosis in pre-PMF considered by the latter as one of the minor diagnostic criteria which seems unwarranted. In contrast to the revised 4th edition, the majority of the microscopic images used for the WHO 5th due to their low magnification and poor technique, do not highlight the diagnosis differences among these entities.
关于原发性血小板增多症（ET）、原发性骨髓纤维化（PMF）以及真性红细胞增多症（PV）的诊断标准，学界始终存在活跃讨论，尤其涉及早期/纤维化前期骨髓纤维化（pre-PMF）这一疾病实体。该概念最初由2001年发布的第三版世界卫生组织（WHO）分类引入，其定义与诊断标准随时间的推移不断修订。pre-PMF的最新定义可见于2022年发布的《国际共识分类》（ICC）。近期发布的WHO第五版分类（2024年）也纳入了一项大致相似的最新定义。截至2016/17年修订的WHO第四版分类，ET的诊断标准已历经多次调整，特别是血小板阈值有所降低，且“真性”与“假性”ET（实为pre-PMF）的重要区分已得到广泛认可。为避免早期PV的误诊，血红蛋白/血细胞比容的性别调整阈值已下调，并将适当的骨髓形态学识别提升为主要诊断标准。鉴于形态学在MPN相关诊断流程中的突出作用，骨髓活检（样本获取与规范实验室处理）的诊断适宜性虽在前几版WHO分类及ICC中均被强调，却未在WHO第五版中具体阐述。两种分类体系均认可遗传标志物的关键作用。通过比较修订后的WHO第四版分类、ICC与WHO第五版，可见除后者将pre-PMF中出现幼红幼粒细胞增多列为次要诊断标准（这一做法似乎缺乏充分依据）外，并无显著差异。与修订后的第四版相比，WHO第五版所采用的大部分显微图像因放大倍数低且技术欠佳，未能清晰凸显这些疾病实体间的诊断差异。
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