Differential diagnosis of clonal versus reactive cytopenia and monocytosis, respectively, frequently presents a diagnostic challenge. With the two recent classifications of myeloid disorders, mutational analysis has gained importance as a diagnostic tool. However, reports on its utility on trephine bone marrow biopsies (BMB) are sparse. The aim of our proof of principle study was to determine the suitability of targeted sequencing for the longitudinal evaluation of cytopenia and monocytosis and demonstration of clonal evolution on sequential BMB. Seventy-seven EDTA-decalcified BMB of 33 patients with peripheral cytopenia and/or monocytosis, including at least one follow-up biopsy/patient, were included. Initial morphological diagnoses were idiopathic cytopenia of undetermined significance (ICUS, 8 cases), MDS (without blast increase, 7 cases), MDS with increased blasts/excess blasts (MDS-IB/EB) (11 cases), and CMML (7 cases). Thirty-one genes relevant for myeloid disorders were examined using two custom AmpliSeq NGS panels. Mutations were found in the initial BMB of 5/8 cases of ICUS, thus changing the diagnosis to clonal cytopenia of unknown significance (CCUS), 5/7 MDS, 10/11 MDS-IB/EB, and 7/7 CMML. Clonal evolution was observed in 14/33 (42%) cases, mostly associated with disease progression. None of the wild-type patients acquired mutations during follow-up. NGS-based mutation profiling is a robust diagnostic tool for BMB and provides valuable additional information, especially for cases with no/minimal dysplasia, and for better risk stratification of MDS. Tracking variant allele frequency and appearance of mutations over time allows for observing clonal evolution or relapse.

克隆性与反应性血细胞减少症和单核细胞增多症的鉴别诊断经常带来诊断挑战。随着最近对髓系疾病的两种分类，突变分析作为一种诊断工具变得越来越重要。然而，关于其在环钻骨髓活检 （BMB） 中的效用的报道很少。我们的原理验证研究的目的是确定靶向测序对血细胞减少症和单核细胞增多症的纵向评估以及序贯 BMB 克隆进化证明的适用性。纳入 33 例外周血细胞减少症和/或单核细胞增多症患者的 77 例 EDTA 脱钙 BMB，包括至少一名随访活检/患者。初始形态学诊断为意义未明的特发性血细胞减少症 （ICUS， 8 例） 、MDS （无原始细胞增加， 7 例）、MDS 伴原始细胞增加 （MDS-IB/EB） （11 例） 和 CMML （7 例）。使用两个定制的 AmpliSeq NGS 检测组合检测了 31 个与骨髓疾病相关的基因。在 5/8 例 ICUS 的初始 BMB 中发现突变，从而将诊断更改为意义不明的克隆性血细胞减少症 （CCUS） 、 5/7 MDS 、 10/11 MDS-IB/EB 和 7/7 CMML。在 14/33 （42%） 病例中观察到克隆进化，主要与疾病进展有关。野生型患者在随访期间均未获得突变。基于 NGS 的突变分析是 BMB 的可靠诊断工具，可提供有价值的附加信息，特别是对于无/轻微异型增生的病例，以及更好的 MDS 风险分层。跟踪变异等位基因频率和突变随时间的出现可以观察克隆进化或复发。