Minimal residual disease (MRD) monitoring has a strong prognostic value in childhood lymphoblastic leukemia (ALL) and is currently utilized in all major pediatric ALL protocols. MRD monitoring is done by multiparameter flow cytometry, IG/TCR quantitative PCR or reverse transcriptase quantitative PCR of leukemic fusion transcripts providing a reliable measurement of treatment response. However, occasionally bone marrow (BM) aspirates may not yield representative material or be misinterpreted due to treatment-induced changes in MRD marker profile, undetected subclones at diagnosis, contamination with peripheral blood or cell adhesion and stroma cell interactions posing a risk for underestimating MRD levels and misclassifying resistant disease that may be detected by traditional BM morphology methods, immunohistochemistry, karyotyping and FISH. We present four cases with high MRD levels where MRD monitoring failed to provide the correct stratification information. Through these cases we discuss the continued need to consider all available information including BM smears, touch imprints and trephine biopsy preparations not only at diagnosis but throughout remission monitoring in pediatric ALL.

中文翻译：

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在评估小儿急性淋巴细胞白血病的疾病状态时，最少的残留疾病监测不能完全替代骨髓形态。

最小残留疾病（MRD）监测对儿童淋巴母细胞白血病（ALL）具有很强的预后价值，目前已在所有主要的儿科ALL方案中使用。可通过多参数流式细胞仪，IG / TCR定量PCR或逆转录酶定量PCR进行白血病融合转录本的MRD监测，从而可靠地测量治疗反应。但是，由于治疗引起的MRD标志物谱变化，诊断时未检测到亚克隆，外周血或细胞粘附污染以及基质细胞相互作用，偶尔会吸出骨髓（BM）或产生误导性材料，可能会低估MRD可以通过传统的BM形态学方法，免疫组织化学，核型分析和FISH检测出耐药性水平和分类错误。我们介绍了4个具有较高MRD级别的案例，其中MRD监视未能提供正确的分层信息。通过这些案例，我们讨论了仍然需要考虑所有可用信息，包括BM涂片，接触印记和环戊铁活检制剂，不仅在诊断时，而且在小儿ALL的整个缓解监测中都应考虑。