Detecting hypodiploidy with endoreduplication and masked hypodiploidy in B-cell acute lymphoblastic leukemia using multicolor flow cytometry.

BACKGROUND: Multicolor flow cytometry-based DNA-ploidy (MFC-ploidy) analysis is a simple, sensitive, and popular method for ploidy analysis in B-cell acute lymphoblastic leukemia (B-ALL). However, the utility of MFC-ploidy in the detection of B-ALL with endoreduplication or masked hypodiploidy has not been reported. Herein, we studied the patterns of MFC-ploidy assessment and its utility to detect B-ALL with hypodiploidy and endoreduplication. METHODS: MFC-ploidy analysis was performed using FxCycle Violet-dye-based method, and cytogenetic ploidy was evaluated using chromosomal-counting and FISH analysis. A total of 20 B-ALL cases with endoreduplication were studied for the patterns of MFC-ploidy analysis and compared with 250 patients with hyperdiploidy and 11 cases with pure hypodiploidy. RESULTS: All B-ALL with endoreduplication revealed two distinct peaks (populations) on MFC-ploidy analysis: the first (hypodiploid) peak (median-DNA-index [DI], 0.82; range, 0.6-0.95) and the second (hyperdiploid) peak with almost twice DI (median-DI, 1.53; range, 1.14-1.75). Cytogenetic findings were available in 19 cases and confirmed hypodiploidy with endoreduplication in 13/19 (68.4%) and only hypodiploidy in 3/19 cases. The remaining three cases showed hyperdiploid blasts in cytogenetic studies. Of these three, two cases had <10% blasts population with hypodiploidy. Thus, masked-hypodiploidy could be diagnosed correctly in 3/19 cases on MFC-ploidy analysis. CONCLUSION: MFC-ploidy analysis shows a characteristic pattern of DNA-ploidy in samples with endoreduplication. It allows the distinction between samples with masked hypodiploidy from true hyperdiploidy. An integrated approach involving cytogenetic and MFC-ploidy detection is very helpful in the risk stratification of B-ALL in routine clinical practice.

Mast cell differentiation of leukemic blasts in diverse myeloid neoplasms: A potential pre-myelomastocytic leukemia condition.

INTRODUCTION: Myeloid neoplasm with blasts showing mast cell (MC)-differentiation and MC-component less than 10% of all nucleated cells but not fulfilling the criteria for systemic mastocytosis with associated hematological neoplasm (SM-AHN) or myelomastocytic leukemia (MML) has not been described in the literature. Herein, we report a study of diverse myeloid malignancies with blasts showing MC-differentiation but not meeting the criteria for SM-AHN or MML. We also evaluated the utility of flow-cytometric immunophenotyping (FCI) in the characterization of immature-MCs (iMCs). METHODS: We identified nine patients of myeloid neoplasms and studied their morphological, FCI, immunohistochemistry, cytogenetic and molecular characteristics. We also compared the immunophenotypic features of MCs from patient samples with control samples. RESULTS: The study included patients with newly-diagnosed acute myeloid leukemia (n = 4), chronic myelomonocytic leukemia (n = 1), and chronic myeloid leukemia on follow-up (n = 4) showing MC differentiation in leukemic-blasts. These patients had mildly increased MCs (range, 0.5%-3%) in bone-marrow morphology, including immature-forms and did not meet the criteria for either SM-AHN or MML. On FCI, iMCs were positive for bright-CD117, heterogeneous-CD34, dim-to-negative-HLADR, and moderate-CD203c expression. Expression-levels of CD123 and CD38 were higher (p < 0.001) but CD33 and CD45 were lower in iMCs compared to mature-MC from control samples (p = 0.019 and p = 0.0037). CONCLUSION: We reported a rare finding of MC differentiation of leukemic blasts in diverse myeloid neoplasms and proposed it as a potential pre-myelomastocytic leukemia condition. We described the distinct immunophenotypic signature of immature-MCs using commonly used markers and highlighted the utility of FCI for the diagnosis of this entity.

Utility of CD36 as a novel addition to the immunophenotypic signature of RAM-phenotype acute myeloid leukemia and study of its clinicopathological characteristics.

INTRODUCTION: In 2016, Children Oncology Group (COG) described a new high-risk subtype of acute myeloid leukemia (AML) with a distinct immunophenotypic-signature, RAM-phenotype (RAM-AML). Data on clinical and laboratory features of RAM-AML are still limited to COG report only. Herein, we report the clinicopathological characteristics and detailed immunophenotypic features of RAM-AML patients. In COG report, 38% of RAM-AML belonged to acute megakaryoblastic leukemia (AMKL)-subtype. Hence, we further compared the immunophenotypic features RAM-AML with non-RAM-AMKL diagnosed during the same study period. METHODS: We included RAM-AML and non-RAM AMKL patients diagnosed between January 2017 and December 2019. We studied their morphological, cytochemical, immunophenotyping, cytogenetic, and molecular characteristics. Mean fluorescent intensity (MFI) and expression-pattern of immunophenotypic markers of RAM-AML were compared with non-RAM AMKLs patients. RESULTS: We identified 11 RAM-AML (1%) and 21 non-RAM AMKL (1.9%) patients in 1102 pediatric-AML patients. Seven of 11 (63.64%) patients belonged to FAB-M7-subtype. CD56, CD117, and CD33 demonstrated overexpression, whereas CD45 and CD38 showed under-expression in RAM-AML patients. CD36 was consistently negative in RAM-AML, whereas moderate-bright positive in non-RAM AMKLs patients (p < 0.0001). On principle component analysis, addition of CD36 enhanced the visual-separation between RAM-AML and non-RAM AMKL clusters. Cytogenetic and molecular studies did not show any recurrent abnormality; however, RNA-sequencing study revealed CBFA2T3-GLIS2-fusion in three of seven (42.8%) RAM-AML patients. CONCLUSION: We report the clinicopathological characteristics and the detailed immunophenotypic profile in the world's second series of RAM-AML patients. We further report a novel finding of CD36-negative expression as an additional parameter to the multidimensional immunophenotypic signature of this entity.

Eleven-marker 10-color flow cytometric assessment of measurable residual disease for T-cell acute lymphoblastic leukemia using an approach of exclusion.

Measurable/minimal residual disease (MRD) status has been suggested as a powerful indicator of clinical-outcome in T-cell lymphoblastic leukemia/lymphoma (T-ALL). Multicolor flow cytometric (MFC)-based T-ALL MRD reports are limited and traditionally based on the utilization of markers-of-immaturity like TdT and CD99. Moreover, studies demonstrating the multicolor flow cytometric (MFC) approach for the assessment of T-ALL MRD are sparse. Herein, we describe an 11-marker, 10-color MFC-based T-ALL MRD method using an "approach of exclusion." METHODS: The study included 269 childhood T-ALL patients treated with a modified-MCP841 protocol. An 11-marker, 10-color MFC-based MRD was performed in bone marrow (BM) samples at the end-of-induction (EOI) and end-of-consolidation (EOC) time-points using Kaluza-version-1.3 software. RESULTS: We studied EOI-MRD in 269 and EOC-MRD in 105 childhood T-ALL patients. EOI-MRD was detectable in 125 (46.5%) samples (median, 0.3%; range, 0.0007-66.3%), and EOC-MRD was detectable in 34/105 (32.4%) samples (median, 0.055%; range, 0.0008-27.6%). Leukemia-associated immunophenotypes (LAIPs) found useful for MRD assessment were dual-negative CD4/CD8 (40.9%), dual-positive CD4/CD8 (23.3%) and only CD4 or CD8 expression (35.8%); dim/subset/dim-negative surface-CD3 (39%), dim/subset/dim-negative/negative CD5 (28.3%), dim/dim-negative/negative/heterogeneous CD45 (44.7%) and co-expression of CD5/CD56 (7.5%). EOI-MRD-positive status was found to be the most-relevant independent factor in the prediction of inferior relapse-free and overall survival. CONCLUSION: We described an 11-marker 10-color MFC-based highly sensitive MRD assay in T-ALL using an approach of exclusion. The addition of CD4 and CD8 to the pan-T-cell markers in a 10-color assay is highly useful in T-ALL MRD assessment and extends its applicability to almost all T-ALL patients.

Post-induction Measurable Residual Disease Using Multicolor Flow Cytometry Is Strongly Predictive of Inferior Clinical Outcome in the Real-Life Management of Childhood T-Cell Acute Lymphoblastic Leukemia: A Study of 256 Patients.

Background: Measurable/minimal residual disease (MRD) status is suggested as a powerful indicator of clinical-outcome in T-cell lymphoblastic leukemia/lymphoma (T-ALL). Contrary to B-cell ALL, reports on T-ALL MRD are limited and mostly based on molecular methods, mainly from developed countries. Multicolor flow cytometry (MFC)-based T-ALL studies are very few. Clinically relevant cut-off levels and ideal time-point for MRD assessment are still inconclusive. In view of lack of T-ALL MRD data from the developing world, we evaluated the prognostic value of MFC-based post-induction (PI)-MRD assessment in T-ALL in the context of standard practice. Methods: We included 256 childhood-T-ALL patients (age < 15 years) treated with a modified-MCP841 protocol, which uses high-dose cytarabine during consolidation, as a part of standard hospital practice. MRD was studied using 10-color 11-antibody MFC with any level of detectable disease being considered positive. Post-induction (PI)-MRD was available in all patients, and post-consolidation (PC) MRD was available mostly in PI-MRD-positive patients (n = 88). Results: Three years cumulative-incidence-of-relapse (3years-CIR) in PI-MRD-positive patients was inferior to negative patients (46.3% vs. 18.4%). The median relapse-free-survival (RFS), event-free-survival (EFS) and overall-survival (OS) with hazard ratio (HR) of PI-MRD-positive patients were 21.4 months vs not reached (p < 0.0001, HR-4.7), 21.6 months vs. not-reached (p = 0.0003, HR-2.01) and 37.3 months vs. not reached (p = 0.026, HR-1.64) respectively. RFS, EFS and OS of patients with PI-MRD<0.01% (n = 17) were as inferior as PI-MRD ≥ 0.01% in comparison with MRD-negative patients with HR of 4.7 (p < 0.0001), 2.45 (p = 0.0003), and 2.5 (p = 0.029), respectively. Three-years-CIR of patients with hyperleukocytosis (≥100 × 109/L) was also higher (50.5 vs. 27.6%) with inferior RFS, EFS, and OS. Among PI-MRD-positive patients, 3years-CIR, RFS, EFS, and OS of PC-MRD-positive were also inferior to that of negative patients. On multivariate analysis any-level detectable PI-MRD and hyperleukocytosis remained independently associated with inferior RFS, EFS, and OS. A combination of PI-MRD-positive status and hyperleukocytosis identified the patients with the worst clinical outcomes. Conclusion: Detectable PI-MRD using MFC was found to be the strong predictive factor of inferior clinical outcome in T-ALL patients. The combination of PI-MRD status and hyperleukocytosis provides the most influential tool for the management of T-ALL in resource constrained settings from developing world.

Flow cytometric evaluation of CD38 expression levels in the newly diagnosed T-cell acute lymphoblastic leukemia and the effect of chemotherapy on its expression in measurable residual disease, refractory disease and relapsed disease: an implication for anti-CD38 immunotherapy.

BACKGROUND: Recently, anti-CD38 monoclonal antibody (Mab) therapy has become a focus of attention as an additional/alternative option for many hematological neoplasms including T-cell acute lymphoblastic leukemia (T-ALL). It has been shown that antitumor efficacy of anti-CD38-Mab depends on the level of CD38 expression on tumor cells. Reports on CD38 expression in T-ALL are scarce, and data on the effect of cytotoxic chemotherapy on CD38 expression are limited to very few samples. Moreover, it lacks entirely in refractory disease and in adult T-ALL. We report the flow cytometric evaluation of CD38 expression in T-ALL blasts at diagnosis and the effect of cytotoxic chemotherapy on its expression in measurable residual disease (MRD), refractory disease (MRD≥5%), and relapsed disease in a large cohort of T-ALL. METHODS: The study included 347 samples (188 diagnostic, 100 MRD, 24 refractory and 35 relapse samples) from 196 (children: 85; adolescents/adults: 111) patients with T-ALL. CD38-positive blasts percentages (CD38-PBPs) and expression-intensity (mean fluorescent intensity, CD38-MFI) were studied using multicolor flow cytometry (MFC). MFC-based MRD was performed at the end-of-induction (EOI-MRD, day 30-35) and end-of-consolidation (EOC-MRD, day 78-85) subsequent follow-up (SFU-MRD) points. RESULTS: Patients were classified into early thymic precursor subtype of T-ALL (ETPALL, 54/188, 28.7%), and non-ETPALL (134/188, 71.3%). Of 188, EOI-MRD assessment was available in 152, EOC-MRD was available in 96 and SFU-MRD was available in 14 patients. CD38 was found positive in 97.9% (184/188) of diagnostic, 88.7% (110/124) MRD (including 24-refractory) and 82.9% (29/35) relapsed samples. Median (95% CI) of CD38-PBPs/MFI in diagnostic, MRD, refractory, and relapsed T-ALL samples were, respectively, 85.9% (82.10%-89.91%)/4.2 (3.88-4.47), 74.0% (58.87%-83.88%)/4.6 (3.67-6.81), 79.6% (65.25%-96.11%)/4.6 (3.33-8.47) and 85.2% (74.48%-93.01%)/5.6 (4.14-8.99). No significant difference was noted in CD38 expression between pediatric versus adult and patients with ETPALL versus non-ETPALL. No change was observed in CD38-MFI between diagnostic versus MRD and diagnostic versus relapsed paired samples. However, we noticed a mild drop in the CD38-PBPs in MRD samples compared with the diagnostic samples (p=0.016). CONCLUSION: We report an in-depth analysis of CD38 expression in a large cohort of T-ALL at diagnosis, during chemotherapy, and at relapse. Our data demonstrated that CD38 is robustly expressed in T-ALL blasts with a little effect of cytotoxic chemotherapy making it a potentially effective target for antiCD38-Mab therapy.

CD304/neuropilin-1 is a very useful and dependable marker for the measurable residual disease assessment of B-cell precursor acute lymphoblastic leukemia.

BACKGROUND: Measurable residual disease (MRD) assessment using multicolor flow cytometry (MFC) has become the center point of pediatric B-cell precursor acute lymphoblastic leukemia (BCP-ALL) risk stratification and therapeutic management. The addition of new markers can improve the accuracy and applicability of MFC-based MRD assay further. Herein, we evaluated the utility of a new marker, CD304/neuropilin-1, in the assessment of MFC-based MRD. METHODS: Expression patterns of CD304 were studied in leukemic blasts from BCP-ALL patients and in normal precursor B cells (NPBC) from uninvolved non-BCP-ALL bone marrow samples using 10-color MFC. MRD was monitored at end-of-induction (EOI; Days 35-40) and end-of-consolidation (Day 78-80) time points. RESULTS: We studied CD304 expression in 300 pediatric BCP-ALL patients and found it positive in BCP-ALL blasts in 41.7% of diagnostic samples. It was significantly associated with ETV6-RUNX1 (p < .001) as well as BCR-ABL1 (p = .019) and inversely associated with TCF3-PBX1 fusion gene (p = .0012). It was found clearly negative in NPBC. EOI-MRD was detectable in 152/300 (50.7%; ≥0.01% in 35.33% and <0.01% in 15.33%) samples, in which CD304 was positive in 72/152 (47.4%) diagnostic and 63/152 (41.4%) MRD samples. It was positive in 45.7% (21/46) of low-level (<0.01%) MRD samples. In comparison with diagnostic samples, its expression was retained in 68.06% (49/72), lost in 31.94% (23/72), and gained in 14/80 (17.5%) of EOI-MRD samples. CONCLUSIONS: CD304 is commonly expressed in leukemic blasts of BCP-ALL. It is very useful in distinguishing residual disease from hematogones and is a fairly dependable marker. Hence, it is a valuable addition for enhancing the sensitivity and applicability of MFC-based MRD assay in BCP-ALL.

A High-Sensitivity 10-Color Flow Cytometric Minimal Residual Disease Assay in B-Lymphoblastic Leukemia/Lymphoma Can Easily Achieve the Sensitivity of 2-in-106 and Is Superior to Standard Minimal Residual Disease Assay: A Study of 622 Patients.

BACKGROUND: Flow-cytometric minimal residual disease (FC-MRD) monitoring is a well-established risk-stratification factor in B-lymphoblastic leukemia/lymphoma (-B-ALL) and is being considered as a basis for deintensification or escalation in treatment protocols. However, currently practiced standard FC-MRD has limited sensitivity (up to 0.01%) and higher false MRD-negative rate. Hence, a highly sensitive, widely applicable, and easily reproducible FC-MRD assay is needed, which can provide a reliable basis for therapeutic modifications. METHODS: A 10-color high-event analysis FC-MRD assay was studied for the evaluation of MRD status at postinduction, (PI; day-35), postconsolidation, (PC; day-78), and subsequent follow-up time-points (SFU) in bone marrow samples from pediatric B-ALL. RESULTS: One-thousand MRD samples (PI-62.2%; PC-26.5%; and SFU-11.3%) from 622 childhood B-ALL patients were studied. High-event analysis was performed with median 4,452,000 events (range, 839,000 to 8,866,000 events) and >4 million events in 71% samples. MRD was measurable in 43.2% of PI-samples, in 29.4% PC-samples, and in 32.7% SFU-samples. To simulate comparison with standard FC-MRD, we reanalyzed MRD results gating only first 500,000 and first 1000,000 events in 122 PI-MRD positive samples with MRD levels <0.02%. Of these samples gated for 500,000 events and 1000,000 events, 32% and 21.3% were found to be falsely MRD-negative, respectively. CONCLUSIONS: We report an easily reproducible high-sensitivity 10-color FC-MRD assay with the sensitivity of 2-in-106 (0.0002%). It allowed the detection of low-level MRD in samples, which could have been reported negative using the standard FC-MRD with limited event analysis. Thus, this high-sensitivity MRD-methodology can provide a reliable basis for therapeutic modifications in B-ALL. © 2019 International Clinical Cytometry Society.

Utility of Immunophenotypic Measurable Residual Disease in Adult Acute Myeloid Leukemia-Real-World Context.

Introduction: One of the mainstays of chemotherapy in acute myeloid leukemia (AML) is induction with a goal to achieve morphological complete remission (CR). However, not all patients by this remission criterion achieve long-term remission and a subset relapse. This relapse is explained by the presence of measurable residual disease (MRD). Methods: We accrued 451 consecutive patients of adult AML (from March 2012 to December 2017) after informed consent. All patients received standard chemotherapy. MRD testing was done at post-induction and, if feasible, post-consolidation using 8- and later 10-color FCM. Analysis of MRD was done using a combination of difference from normal and leukemia-associated immunophenotype approaches. Conventional karyotyping and FISH were done as per standard recommendations, and patients were classified into favorable, intermediate, and poor cytogenetic risk groups. The presence of FLT3-ITD, NPM1, and CEBPA mutations was detected by a fragment length analysis-based assay. Results: As compared to Western data, our cohort of patients was younger with a median age of 35 years. There were 62 induction deaths in this cohort (13.7%), and 77 patients (17.1%) were not in morphological remission. The median follow-up was 26.0 months. Poor-risk cytogenetics and the presence of FLT3-ITD were significantly associated with inferior outcome. The presence of post-induction MRD assessment was significantly associated with adverse outcome with respect to OS (p = 0.01) as well as RFS (p = 0.004). Among established genetic subgroups, detection of MRD in intermediate cytogenetic and NPM1 mutated groups was also highly predictive of inferior outcome. On multivariate analysis, immunophenotypic MRD at the end of induction and FLT3-ITD emerged as independent prognostic factors predictive for outcome. Conclusion: This is the first data from a resource-constrained real-world setting demonstrating the utility of AML MRD as well as long-term outcome of AML. Our data is in agreement with other studies that determination of MRD is extremely important in predicting outcome. AML MRD is a very useful guide for guiding post-remission strategies in AML and should be incorporated into routine treatment algorithms.

Evaluation of CD229 as a new alternative plasma cell gating marker in the flow cytometric immunophenotyping of monoclonal gammopathies.

BACKGROUND: Current flow-cytometric plasma cell (PC) gating is based on CD138, CD38, and CD45 expression. CD138 is known for variable expression and loss during storage and processing. Introduction of anti-CD38 and anti-CD138 monoclonal-antibody therapies has limited the use of these markers during follow-up. Hence, additional reliable PC-gating markers are required. Recently, CD229 has been claimed as an alternative PC-gating marker. However, these studies are limited to a small cohort of samples. We evaluated the utility of CD229 as a new PC-gating marker in routine laboratory practice. METHODS: Expression of CD229 was studied in 310 bone marrow (BM) samples (251 plasma-cell disorders and 59 controls) and compared with CD138 and CD38 expression. We also evaluated the effect of additional processing for cytoplasmic immunoglobulin-light-chains (CyIgL) staining on the quantitation of PC. RESULTS: Expression of CD229 was consistently stronger on PC than other hematopoietic-cells (p < 0.001). PC-percentages using CD229 in combination with CD38 or CD138 and CD45 revealed high correlation with a reference gating-strategy using CD138, CD38 and CD45 (r = 0.98, r = 0.99 r = 0.99 respectively) and r = 0.92 using CD229 and CD45 without CD38 or CD138. In contrast, CD138 expression showed significant variability (CV-MFI, 97.5) and loss from PC in 53% of samples. Quantitation of PC was found to be lower in 69.3% and higher in 30.7% samples processed for CyIgL-staining as compared to surface-staining. CONCLUSIONS: CD229 is a reliable new alternative PC-gating marker in routine laboratory practice. Quantitation of PC based on CD138 expression or from samples processed for CyIgL-staining should be used with caution. © 2018 International Clinical Cytometry Society.

Evaluation of new markers for minimal residual disease monitoring in B-cell precursor acute lymphoblastic leukemia: CD73 and CD86 are the most relevant new markers to increase the efficacy of MRD 2016; 00B: 000-000.

BACKGROUND: Multiparametric flow cytometry (MFC) is a popular technique for minimal residual disease (MRD) analysis. However, its applicability is still limited to 90% of B-cell precursor acute lymphoblastic leukemia (BCPALL) due to two major issues, i.e. a proportion of cases do not express adequate leukemia associated immunophenotype (LAIPs) with currently used markers and drug-induced antigen modulation. Hence, the incorporation of additional reliable markers is required for the further improvement of MFC-based MRD evaluation. We studied the utility of new markers in improvising MFC-based MRD detection in BCPALL. METHODS: Expression-patterns of six new markers, i.e. CD24, CD44, CD72, CD73, CD86, and CD200 were studied in leukemic-blasts from ninety childhood BCPALL patients and in hematogones from 20 uninvolved staging bone marrow (BM) and ten postinduction non-BCPALL BM samples using eight-color MFC. The utility of these new markers in the day 35 postinduction MRD evaluation was determined. RESULTS: Frequencies of LAIPs of CD73, CD86, CD72, CD44, CD200, and CD24 in diagnostic samples were 76.7, 56.7, 55.6, 50, 28.9, and 20%, respectively. Differential expression of all new markers was highly significant (P < 0.01) between early (CD10+ CD19+ CD34+) hematogones, late (CD10+ CD19+ CD34-) hematogones and BCPALL blasts except between early hematogones and BCPALL blasts for CD200 (P = 0.1). In MRD-positive samples, CD73 showed the maximum (83%) frequency of LAIP and CD86 showed the highest (100%) stability of aberrant expression. Inclusion of CD73 and CD86 increased the applicability of MFC-MRD assay to 98.9% MRD samples. CONCLUSION: CD73 and CD86 are the most relevant markers to incorporate in the routine MRD evaluation of BCPALL. © 2016 International Clinical Cytometry Society.

Method for DNA Ploidy Analysis Along with Immunophenotyping for Rare Populations in a Sample using FxCycle Violet.

The clinical use of flow cytometric DNA ploidy assay has been extended towards stratifying the risk of diseases, such as monoclonal gammopathies or B cell acute lymphoblastic leukemia, and to detect circulating tumor cells, both of which require detection of minute cell populations. This unit describes a protocol for determining DNA ploidy in fixed samples with simultaneous surface immunophenotyping. It is an easy method for simultaneous 6- to 8-color immunophenotyping and DNA content analysis using FxCycle Violet (FCV; DAPI) dye. This protocol is a one-step modification of routine multicolor immunophenotyping that includes surface staining followed by fixation and then DNA staining with FCV. It utilizes mature lymphocytes from the sample as an internal control for determination of DNA index. It is a sensitive method that allows DNA-ploidy determination and cell cycle analysis in a rare tumor population as low as 100 events, as well as DNA ploidy determination in various subsets of hematopoietic cells in the same sample based on their immunophenotype. © 2017 by John Wiley & Sons, Inc.

A novel and easy FxCycle™ violet based flow cytometric method for simultaneous assessment of DNA ploidy and six-color immunophenotyping.

Abnormal DNA ploidy is a valuable prognostic factor in many neoplasms, especially in hematological neoplasms like B-cell acute lymphoblastic leukemia (B-ALL) and multiple myeloma (MM). Current methods of flow-cytometric (FC) DNA-ploidy evaluation are either technically difficult or limited to three- to four-color immunophenotyping and hence, challenging to evaluate DNA-ploidy in minute tumor population with background rich of its normal counterpart cells and other hematopoietic cells. We standardized a novel sensitive and easy method of simultaneous evaluation of six- to seven-color immunophenotyping and DNA-ploidy using a dye-FxCycle Violet (FCV). Linearity, resolution, and coefficient of variation (CV) for FCV were studied using chicken erythrocyte nuclei. Ploidy results of FCV were compared with Propidium iodide (PI) in 20 samples and intra-assay variation for FCV was studied. Using this six-color immunophenotyping & FCV-protocol DNA-ploidy was determined in bone-marrow samples from 124 B-ALL & 50 MM patients. Dilution experiment was also conducted to determine the sensitivity in detection of aneuploidy in minute tumor population. FCV revealed high linearity and resolution in 450/50 channel. On comparison with PI, CV of Go/G1-peak with FCV (mean-CV 4.1%) was slightly higher than PI (mean-CV 2.9%) but had complete agreement in ploidy results. Dilution experiment showed that aneuploidy could be accurately detected up to the limit of 0.01% tumor cells. Intra-assay variation was very low with CV of 0.005%. In B-ALL, hypodiploidy was noted in 4%, hyperdiploidy in 24%, near-hyperdiploidy in 13% and remaining 59% were diploid. In MM, hypodiploidy was in 2%, hyperdiploidy in 58%, near-hyperdiploidy in 8% and remaining 30% were diploid. FCV-based DNA-ploidy method is a sensitive and easy method for simultaneous evaluation of six-color immunophenotyping and DNA analysis. It is useful in DNA-ploidy evaluation of minute tumor population in cases like minimal residual disease and MM precursor conditions.

Blastic plasmacytoid dendritic cell neoplasm: report of two pediatric cases.

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare subtype of acute leukemia that typically follows a highly aggressive clinical course in adults, whereas experience in children with this disease is very limited. We report cases of two children in whom bone marrow showed infiltration by large atypical monocytoid 'blast-like' cells which on immunophenotyping expressed CD4, CD56, HLA-DR and CD33 while were negative for CD34 other T-cell, B-cell and myeloid markers. The differential diagnoses considered were AML, T/NK-cell leukemia and acute undifferentiated leukemia. Additional markers CD303/BDCA-2 and CD123 which are recently validated plasmacytoid dendritic cell markers were done which helped us clinch the diagnosis of this rare neoplasm. An accurate diagnosis of BPDCN is essential in order to provide prompt treatment. Due to its rarity and only recent recognition as a distinct clinicopathological entity, no standardized therapeutic approach has been established for BPDCN.

Morphological spectrum of leukemic mantle cell lymphoma.

BACKGROUND: Leukemic involvement in mantle cell lymphoma (MCL) is common, and can be secondary to nodal or extranodal disease or can be de-novo. There is paucity of literature that describes the morphological spectrum. AIM: This study was aimed at studying the morphological spectrum of leukemic MCL and to correlate the morphology with other features. MATERIALS AND METHODS: Twenty six such cases diagnosed over a period of four years were studied. Peripheral blood and bone marrow aspiration smears stained with Wrights stain were examined by three hematopathologists. Immunophenotyping was done using multicolor flow cytometry. Fluorescence in situ hybridization (FISH) done in 12 cases showed t(11;14)(q13:q32). RESULTS: Six cases had de-novo leukemic involvement; while 20 cases had secondary involvement. Morphologically, the cells were small (less than twice the size of red blood cell) or large. Small cell morphology in turn showed irregular nuclear border (n=13) or round nuclear contour (n=6). Large cells had blastic morphology (n=5) or had central prominent nucleoli resembling prolymhphocytes (n=2). Twenty cases showed characteristic immunophenotype of CD5+/CD19+/CD20+/FMC7+/CD10-/CD23- and light chain restrictions. Three cases expressed CD23 and two cases were negative for FMC7. Five out of 12 cases, where FISH was done, showed cytogenetic abnormalities in addition to t(11;14)(q13;q32). CONCLUSION: Morphological spectrum of leukemic MCL ranges from small cells resembling chronic lymphocytic leukemia (CLL) or follicular lymphoma (FL) to large cell mimicking prolymphocytic leukemia (PLL) or acute leukemia. Large cell morphology was associated with more frequent additional cytogenetic abnormality as well as a poorer outcome.