IDH1 和 IDH2 是骨髓造血系统肿瘤中最常见的突变基因之一。有人提出，IDH2 R172 突变（mR172）能定义急性髓系白血病（AML）的一种分子亚型，但 mR172 的临床病理特征尚未完全描述。我们回顾性地鉴定和表征了所有存在增生细胞的 mR172 肿瘤，并与相似数量的 IDH2 R140（mR140）和 IDH1 R132（mR132）突变的肿瘤（n = 39）进行比较。mR172 病例具有较低的白细胞计数和骨髓细胞密度，mR172 肿瘤常表现为具有高度内凹、割裂的细胞核的增生细胞，通常表达 CD34、HLA-DR、CD117 和 CD13，但经常表现为 CD33 下降。mR172 病例经常有共存的骨髓增生异常相关基因突变和/或不良染色体型。尽管频繁出现不良风险遗传变化，在我们的队列中，mR172 病例与非 mR172 病例相比，总生存期显著提高（P = .01），我们验证了在一个独立的大数据集中 mR172 与更好的生存有关。我们展示了 mR172 肿瘤代表着一种形态学和表型学上不同的亚型，在我们的队列中表现出相对较好的生存，但这种表型学特征还没有被当前 AML 风险评估所捕捉。© 作者 2023。牛津大学出版社代表美国临床病理学会出版。保留所有权利。要获取许可，请发送电子邮件至 journals.permissions@oup.com。

IDH1 and IDH2 are among the most commonly mutated genes in myeloid neoplasms (MNs). It has been proposed that IDH2 R172 mutations (mR172) define a molecular subtype of acute myeloid leukemia (AML), but the clinicopathologic features of AML with mR172 have not been fully described.We retrospectively identified and characterized all mR172 MNs with increased blasts in our archive for comparison to a similar number of MNs with IDH2 R140 (mR140) and IDH1 R132 (mR132) mutations (n = 39).mR172 cases had lower leukocyte counts and bone marrow cellularity than did non-mR172 cases. mR172 MNs often displayed blasts with highly invaginated, cleaved nuclei and typically expressed CD34, HLA-DR, CD117, and CD13 but often with diminished CD33. mR172 cases often had co-occurring mutations in myelodysplasia-associated genes and/or an adverse karyotype. Despite frequent adverse-risk genetic changes, in our cohort mR172 cases had significantly improved overall survival vs non-mR172 cases (P = .01), and we validated that mR172 was associated with improved survival in an independent large data set.We show that MNs with mR172 represent a morphologically and phenotypically distinct subtype, which in our cohort exhibited relatively favorable survival that is not captured in current AML risk assignment.© 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.