Myelodysplastic syndromes (MDS) are a heterogenous group of hematologic malignancies characterized by ineffective hematopoiesis, morphologic dysplasia in myeloid progenitors, and an increased risk for progression to acute myeloid leukemia. Historically, blast enumeration has held significant importance in subtyping MDS, with conventional cytomorphology serving as the gold standard assessment method [1]. Blast percentage was integral to MDS classification using the French-American-British and subsequent 3^rd and 4^th editions of the World Health Organization (WHO) classifications of hematologic malignancies [2,3,4], and blast percentage was one of the variables incorporated into the initial and revised International Prognostic Scoring System (IPSS), clinically used to stratify MDS patients into distinct risk groups [5, 6].

With the advent of relatively low-cost high-throughput sequencing, mutational testing in MDS has been incorporated into clinical practice, and genetically distinct MDS subgroups (such as those with SF3B1 mutation or TP53 inactivation) have been identified [7, 8]. The current 5th edition of the WHO classification (WHO5) and the International Consensus Classification (ICC) both recognize MDS with biallelic TP53 inactivation as a distinct entity even in the setting of a low blast percentage, but historic bone marrow blast percentage thresholds (5–9% and 10–19%) are essentially otherwise retained in both classification systems. Recently, an updated IPSS model (IPSS-M) incorporating mutational data was published, further refining prior IPSS schema that had used structural chromosomal aberrations but no other genetic information [9]. The IPSS-M retained blast percentage in its risk model, but as a continuous rather than a categorial risk variable.

骨髓增生异常综合征 (MDS) 是一组异质性血液恶性肿瘤，其特征为无效造血、髓系祖细胞形态发育不良以及进展为急性髓系白血病的风险增加。从历史上看，原始细胞计数在MDS分型中具有重要意义，传统细胞形态学是金标准评估方法[1]。使用法国-美国-英国以及随后的世界卫生组织 (WHO) 血液恶性肿瘤分类的^第三版和^第四版，母细胞百分比是 MDS 分类的组成部分 [2,3,4]，母细胞百分比是变量之一纳入初始和修订后的国际预后评分系统 (IPSS)，临床上用于将 MDS 患者分为不同的风险组 [5, 6]。

随着相对低成本的高通量测序的出现，MDS 的突变检测已被纳入临床实践，并且已鉴定出遗传上不同的 MDS 亚组（例如具有SF3B1突变或TP53失活的亚组）[7, 8]。目前的第五版 WHO 分类 (WHO5) 和国际共识分类 (ICC) 均将双等位基因TP53失活的 MDS 视为一个独特的实体，即使在原始细胞百分比较低但历史性骨髓原始细胞百分比阈值的情况下也是如此（5- 9% 和 10-19%）在两个分类系统中基本上都保留了。最近，发布了包含突变数据的更新版 IPSS 模型 (IPSS-M)，进一步完善了之前使用结构染色体畸变但没有使用其他遗传信息的 IPSS 模式 [9]。 IPSS-M 在其风险模型中保留了爆炸百分比，但作为连续风险变量而不是分类风险变量。