流式细胞仪（FCM）广泛应用于成熟B细胞肿瘤（MBN）的诊断，且FCM数据通常与形态学所见一致。然而，常见的MBN类型——弥漫大B细胞淋巴瘤（DLBCL）有时无法通过FCM检测出来。本研究旨在探讨增加FCM检测DLBCL失败的可能因素。回顾性整理分析了经过八色FCM的最终诊断为DLBCL的病例。比较了临床、FCM、组织病理学和遗传学数据在被FCM检测到和未被检测到的病例之间的差异。共分析了来自135位不同患者的DLBCL病例，其中22例（16%）未被FCM检测到。在未被流式细胞仪检测到的样本中，淋巴细胞占总细胞数的百分比较低（p = 0.02），而T细胞占总淋巴细胞数的百分比较高（p = 0.01）。免疫组化学中MYC蛋白表达量高的病例较不容易被FCM漏诊（p = 0.011）。DLBCL的检测结果在生发中心B细胞（GCB）和非GCB亚型之间没有差异，没有明显受到坏死或纤维化的影响，或者组织活检与细针穿刺样本之间的差异，并且在淋巴结与非淋巴结组织样本之间的差异也不明显。本研究确定了影响FCM漏诊DLBCL的几个因素。即使进行了八色分析，FCM仍然无法检测到许多DLBCL病例。© 2023 The Authors. International Journal of Laboratory Hematology published by John Wiley & Sons Ltd.

Flow cytometry (FCM) is widely used in the diagnosis of mature B-cell neoplasms (MBN), and FCM data are usually consistent with morphological findings. However, diffuse large B-cell lymphoma (DLBCL), a common MBN, is sometimes not detected by FCM. This study aimed to explore factors that increase the likelihood of failure to detect DLBCL by FCM.Cases with a final diagnosis of DLBCL that were analysed by eight-colour FCM were retrospectively collated. Clinical, FCM, histopathological and genetic data were compared between cases detected and cases not detected by FCM.DLBCL cases from 135 different patients were analysed, of which 22 (16%) were not detected by FCM. In samples not detected by flow cytometry, lymphocytes were a lower percentage of total events (p = 0.02), and T cells were a higher percentage of total lymphocytes (p = 0.01). Cases with high MYC protein expression on immunohistochemistry were less likely to be missed by FCM (p = 0.011). Detection of DLBCL was not different between germinal centre B-cell (GCB) and non-GCB subtypes, not significantly affected by the presence of necrosis or fibrosis, and not significantly different between biopsy specimens compared to fine-needle aspirates, or between samples from nodal compared to extranodal tissue.The study identifies several factors which affect the likelihood of DLBCL being missed by FCM. Even with eight-colour analysis, FCM fails to detect numerous cases of DLBCL.© 2023 The Authors. International Journal of Laboratory Hematology published by John Wiley & Sons Ltd.