Peripheral blood flow cytometry for the diagnosis of pediatric acute leukemia: Highly reliable with rare exceptions

Abstract

Background: Recent data have demonstrated the high sensitivity and specificity of peripheral blood flow cytometry (PBFC) for the diagnosis of pediatric leukemia; however, diagnostically significant immunophenotypic discrepancies between PBFC and bone marrow (BM) evaluation, which result in different lineage assignment and treatment protocols, can rarely occur. Here, we sought to further characterize the performance of PBFC for pediatric leukemia and highlight the exceptions when PBFC can result in misdiagnosis. Methods: An institutional database was searched between 2012 and 2016 for cases of acute leukemia with concurrent PBFC and BM evaluation. Immunophenotyping results from the peripheral blood and BM using four or eight color flow cytometry, as well as BM cytochemical staining and immunohistochemistry, were compared. Results: Two hundred ninety PBFC samples with concurrent BM evaluation were identified. Based on the final immunophenotypic classification, the cases were distributed as follows: 108 B-lymphoblastic leukemia (B-ALL), 57 T-lymphoblastic leukemia (T-ALL), 116 acute myeloid leukemia (AML), and 9 mixed-phenotype acute leukemia (MPAL). Among all cases, five had a diagnostically significant discrepancy between PBFC and BM evaluation. In three cases, the immunophenotype by PBFC was consistent with early T-cell precursor ALL (ETP-ALL), whereas BM evaluation demonstrated MPAL. Two cases were suspicious for acute megakaryoblastic leukemia (AMKL) and MPAL, T/myeloid by PBFC but were diagnosed as B-ALL and T-ALL in the BM. Conclusion: Immunophenotypic classification by PBFC is accurate (>98%) in almost all cases of pediatric leukemia with the rare exceptions of suspected ETP-ALL, MPAL, and AMKL. These PBFC diagnoses should be confirmed with BM immunophenotyping. K E Y W O R D S acute lymphoblastic leukemia, acute myeloid leukemia, early T-cell precursor acute lymphoblastic leukemia, mixed-phenotype acute leukemia, pediatric leukemia, peripheral blood flow cytometry

Cytogenetic aberration in mixed-phenotype acute leukemia in children: A single-center retrospective review

“…Furthermore, T/myeloid MPAL could have considerable immunophenotypic overlap with ETP-ALL but expresses MPO or two defining monocytic markers. 20 MPAL is considered to be high risk with a poor prognosis; however, in a multivariate analysis, age and year of transplant had a favorable impact on outcome. 21 The majority of our cases were children using MRD-guided treatment strategy, correlated with a better leukemia-free survival.…”

Identifying acute lymphoblastic leukemia mimicking juvenile idiopathic arthritis in children

“…Screening for ALL should include LDH, uric acid and ESR, examination for organomegaly, blood smear and/or flow cytometry to detect blasts in peripheral blood. However, sensitivity to detect blasts in peripheral blood is lower when the leukocyte count is low, as is often the case with arthritis [ 24 ].…”

“…Screening for ALL should include LDH, uric acid and ESR, examination for organomegaly, blood smear and/or flow cytometry to detect blasts in peripheral blood. However, sensitivity to detect blasts in peripheral blood is lower when the leukocyte count is low, as is often the case with arthritis [24]. Because patients with ALL can occasionally have normal indices during the prodromal phase of the disease, a referral to a hematologist/oncologist should be considered for reasons other than joint pain or a lack of laboratory markers for inflammatory diseases.…”

Hi-C detects genomic structural variants in peripheral blood of pediatric leukemia patients

“…We expect that simple refinements of the approach we describe could significantly improve the power to detect translocations using peripheral blood. For instance, a simple solution would be to enrich leukemic blasts by performing fluorescence-activated cell sorting directly on peripheral blood ( Rezaei et al 2003 ; Cheng et al 2019 ). This approach would reduce the need for bone marrow biopsies, which can be painful procedures.…”