Immunoalkaline phosphatase labeling of terminal transferase in hematologic samples

Early studies of terminal transferase (TdT) expression in acute leukemia indicated that this enzyme is only found in acute leukemia of lymphoblastic type (ALL). More recently, however, several reports have suggested that TdT-positive blast cells may be found in a substantial number of cases of acute myeloid leukemia (AML). In this study, a sensitive immunoalkaline phosphatase procedure (the APAAP technic) has been used to stain normal and neoplastic blood and bone marrow samples for TdT with the use of both polyclonal and monoclonal anti-TdT antibodies. As expected, most cases of ALL studied (63 of 65) were TdT-positive. In addition, however, blast cells in 22 out of 59 (37%) cases of AML were stained by anti-TdT antibodies. Both nuclear and cytoplasmic localization were seen in each type of acute leukemia. These findings, together with previous immunocytochemical and biochemical studies, suggest that a substantial number of cases of AML express TdT (usually in a minority of blast cells) and that the frequency with which these cases are detected is directly related to the sensitivity of the staining technic used.     

CD64在急性白血病免疫分型中的意义

目的探讨CD64在急性白血病免疫分型中的意义。方法应用直接荧光标记法,经流式细胞术对116例急性髓系白血病(AML)和70例急性淋巴细胞白血病(ALL)进行免疫表型的检测。结果 AML组CD64的表达阳性率明显高于ALL组(41.4%vs 2.9%,P<0.01)。CD64在M5和M4的表达阳性率最高,分别为77.1%和55.6%。CD64的阳性表达率在M0(0)、M1(0)、M2(7.9%)明显低于M3(47.1%)、M4与M5(P<0.01)。各亚型CD64阳性病例中,M4、M5的CD64阳性细胞表达率分别为(62.5±24.7)%、(68.7±25.9)%,均明显高于M2(28.3%±5.7%)、M3(34.3%±6.3%)(P<0.01)。CD64对诊断AML的灵敏度优于CD14,其特异度优于CD117、CD33及CD13。虽然CD64诊断M4\M5的特异度较CD14稍差(82.5%vs 100%),但是灵敏度高于CD14(69.8%vs 41.5%)。结论 CD64可作为辅助诊断AML的髓系标志抗原,有助于提高M4/M5的检出率及其与其他AML亚型的鉴别诊断。     

Chloroacetate esterase positivity in acute lymphoblastic leukemia

Chloroacetate esterase (CAE) reactivity is associated with acute nonlymphocytic leukemia (ANLL) and, to the author's knowledge, has not been reported in acute lymphoblastic leukemia (ALL). The authors have identified a single patient whose blasts displayed CAE reactivity from a review of 400 newly diagnosed patients with ALL. The diagnosis of ALL in this case was based upon morphologic evaluation (FAB:L1), presence of terminal deoxynucleotidyl transferase (TdT), the absence of reactivity with myeloperoxidase, and the failure of leukemic blasts to mark with a panel of anti-myeloid monoclonal antibodies. Remission was induced promptly with standard ALL therapy. This case demonstrates that punctate CAE positivity rarely can occur in ALL, and, therefore, CAE is not entirely specific for ANLL. The authors conclude that CAE positivity should not be used as a sole criterion to diagnose ANLL in the absence of supporting morphologic, cytochemical, immunocytologic, or clinical information.     

Flow cytometric analysis of terminal deoxynucleotidyl transferase

Terminal deoxynucleotidyl transferase (TdT) is a useful marker for lymphoid precursor cells. In this study, the authors used flow cytometry (FCM) to analyze TdT expression in human hematopoietic malignancies. Cells were fixed in 0.5% formaldehyde, briefly exposed to nonionic detergent, and subsequently labeled with mouse monoclonal anti-TdT antibodies followed by fluorescein-conjugated antimouse IgG and propidium iodide (PI), which was used for the simultaneous analysis of DNA content. Cells from 20 of 22 acute lymphoblastic leukemias (ALL), 4 of 7 mixed lineage leukemias, 2 of 21 acute myeloid and myelomonocytic leukemias, 1 of 2 chronic myeloid leukemias in blast crisis, 1 lymphoblastic lymphoma, and 1 thymoma were TdT positive. Cells from 13 nonlymphoblastic lymphomas, 3 myelodysplastic bone marrows, and peripheral blood mononuclear cells from 29 normal individuals were negative. An excellent correlation was seen between this assay, the conventional slide immunofluorescence technique, and an enzyme immunoassay method. The FCM assay detected as few as 2% blasts in mixing experiments of TdT-containing leukemic cells with normal peripheral lymphocytes. Furthermore, the combined analysis of TdT and DNA allowed the recognition of aneuploid TdT positive cells in four cases of ALL. The high sensitivity, the quantitative information obtained, and the capability of simultaneously analyzing DNA content make this method of TdT analysis more valuable than conventional techniques.     

Terminal deoxynucleotidyl transferase (TdT) and membrane receptors in human leukemia and lymphoma — First experience with lyophilized cells

Summary Surface marker analyses and TdT assays were performed on cells from 31 patients. A variety of diagnoses were made and categorized as follows: acute leukemia (group I), non-Hodgkin lymphoma (group II) and diverse diagnoses (group III). Levels of TdT in the range from 0 to 7.9 U/mg lyophilized blasts from the peripheral blood were found in AL. This corresponds to 0–95 U/10⁸ cells. Preparations of mononuclear cells from the peripheral blood of healthy donors showed TdT values up to 0.88 U/mg or 10.6 U/10⁸ cells. High TdT activity was observed in a patient with AML, type M1 according to the FAB classification. In a patient with ALL (L1) cytostatic treatment effected the clearance of TdT activity from the peripheral blood cells and at the same time induced a significant increase of E rosette forming cells. Combined studies of the TdT activity and cell surface markers may enable us to define remissions and relapses of AL more precisely than it is possible by conventional cytological methods.Within the group II two patients with moderate TdT activities of 1.2 and 1.28 U/mg, respectively, were observed whose cells were of prolymphocytic or unclassifiable appearance, respectively. The TdT assay may be helpful to identify such cells of unknown origin and in addition may provide the means of discrimination between such cases and ALL patients who mostly show high TdT activities.Another result of our studies was the finding of moderate TdT activity of 1.2 U/mg with cells from the pleural effusion of a patient with Hodgkin's disease. Cells from malignant effusions from a patient with melanoma and a patient with teratoid carcinoma showed no TdT activity. Cells form the peripheral blood and from the bone marrow of a patient with blast crisis of CML showed TdT activity of 1.52 and 2.72 U/mg, respectively. Two other patients with blast crisis were negative. Not TdT activity was found in leukemic plasma cells.Our results show that lyophilized cells can be used for determinations of TdT activity. This greatly facilitates multi-parameter studies including cytological, cell surface marker and biochemical analyses.

---

Abbrevations PBL peripheral blood lymphocytes - AL acute leukemia - AML acute myeloid leukemia - AUL acute unclassified leukemia - CML chronic myeloid leukemia - ML malign lymphoma of non-Hodgkin type - FCS fetal calf serum - DMSO dimethylsulfoxyde - PBS Dulbeccos phosphate buffered salt solution - SIg surface membrane bound immunoglobulin - ALL acute lymphoblastic leukemia - IF immunofluorescence - EDTA ethylenediamine tetraacetate - LL lymphoblastic lymphoma Supported by Deutsche Forschungsgemeinschaft, Bad Godesberg, We445 and SFB 102     

Evaluation of cerebrospinal fluid mononuclear cells obtained from children with acute lymphocytic leukemia: advantages of combining cytomorphology and terminal deoxynucleotidyl transferase

Sixty cerebrospinal fluid (CSF) samples were obtained from 28 children with terminal deoxynucleotidyl transferase (TdT) positive acute lymphocytic leukemia (ALL). Cell morphology was evaluated using Wright's stained cytocentrifugation prepared slides. The presence of nuclear TdT was detected by an immunofluorescent (IF) assay. Evaluation of CSF mononuclear cells using these two methods simultaneously allowed us to differentiate between leukemic and nonleukemic pleocytosis. Agreement between cytomorphology and TdT in identifying CNS lymphoblasts was found in 55 of 60 samples. Seventy-two per cent of the TdT-positive samples were obtained from children with CSF cell counts less than 10 WBC/mm3. We recommend that these two methods be used in conjunction when evaluating CSF mononuclear cells from children with TdT positive ALL.     

RUNX1 amplification in lineage conversion of childhood B-cell acute lymphoblastic leukemia to acute myelogenous leukemia

Amplification of RUNX1 (alias AML1) is a recurrent karyotypic abnormality in childhood acute lymphoblastic leukemia (ALL) that is generally associated with a poor outcome. It does not occur with other primary chromosomal abnormalities in acute ALL. AML1 amplification in acute myelogenous leukemia (AML) is a rare secondary event described mainly in therapy-related cases. AML1 amplification was found in a 13-year-old patient with AML M4/M5 leukemia that occurred 5 years after she had been diagnosed with common B-cell ALL. Conventional cytogenetic, fluorescent in situ hybridization (FISH), and polymerase chain reaction methods revealed no other chromosomal change expected to occur in a disease that we assumed to be a secondary leukemia. Due to the lack of cytogenetic data from the diagnostic sample, we developed a new approach to analyze the archived bone marrow smear, which had been stained previously with May-Grünwald-Geimsa by the FISH method. This analysis confirmed that in addition to t(12;21), AML1 amplification and overexpression existed already at the time the diagnosis was made. The chromosomal changes, however, were found in different clones of bone marrow cells. While the first course of chemotherapy successfully eradicated the cell line with the t(12;21), the second cell line with AML1 amplification remained latent during the time of complete remission and reappeared with a different immunophenotype.     

Selective reactivity of sera from alloimmunized sheep and cattle against human T and leukemia cells

Human B and T lymphocytes from a panel of healthy individuals were tested against serial dilutions of 68 mare, 81 cow, 7 sow, and 87 ewe sera. All the animals had been alloimmunized by pregnancies andlor blood transfusions. Weak correlations with HLA-A. B. C. and DR specificities were found in 20 sera. Twelve other sera, 9 from ewes and 3 from cows, had a strong reactivity against T lymphocytes but weak or no reactivity against B cells, spleen null cells, granulocytes, and platelets., suggesting a non-major histocompatibility complex (MHC) cross-reactivity. They were cytotoxic for most of the cells of malignant proliferative origin tested thus far, including T acute lymphoblastic leukemia (T ALL), common ALL (cALL), acute mycloblastic leukemia (AML), and Sezary cells, but were negative with B lymphoblastoid cell lines and cells from patients with B chronic lymphocytic leukemia (CLL) and chronic myeclocytic leukemia (CML).The hypothesis that humans and certain other mammals share a common determinant on T-lineage cells and some malignant cells is advanced.     

Acute lymphoblastic leukemia. Survey of immunophenotype, French-American-British classification, frequency of myeloid antigen expression, and karyotypic abnormalities in 210 pediatric and adult cases

Immunophenotypic studies are essential to distinguish acute lymphoblastic leukemia (ALL) from minimally differentiated acute myeloid leukemia (AMLM0) and to classify ALL into immunologic subtypes. Frequently, immunophenotyping identifies myeloid antigen expression in ALL, causing a potential diagnostic problem. To evaluate the immunophenotype of ALL, we studied 210 cases of pediatric and adult ALL by flow cytometry and compared the results with the French-American-British (FAB) Cooperative Group classification and the karyotypic findings. Myeloid-associated antigens were expressed in 78 (45.6%) of precursor B-cell ALL cases. Pediatric precursor B ALLs had a higher frequency of myeloid antigen expression than did adult cases. All mature B-cell ALL cases were negative for TdT and myeloid antigens. Myeloid antigen expression was less frequent in T-cell ALL cases compared with precursor B-cell ALL cases. Of the 192 cases submitted for cytogenetic analysis, 147 were abnormal. The most common chromosomal translocation was the Philadelphia chromosome, which was more likely to have L2 blast morphology and a precursor B immunophenotype. Myeloid antigen expression was present in 70.8% of Ph-positive cases (P = .008). Chromosome rearrangements involving 11q23 also showed an increased frequency of myeloid antigen expression. Chromosome translocations involving regions of T-cell receptor genes were present in 24% of T-cell ALL cases. A high percentage of ALL cases, however, had various other cytogenetic abnormalities, many of which involved less well-studied chromosomal regions.     

Acute lymphoblastic leukaemia: correlation between morphological/immunohistochemical and molecular biological findings in bone marrow biopsy specimens.

BACKGROUND: Although numerous antibodies suitable for use on paraffin wax embedded sections are available for the subtyping of acute leukaemia (acute myelogenous leukaemia (AML) and acute lymphoblastic leukaemia (ALL)) in bone marrow biopsy sections, unequivocal identification of the cell line involved is sometimes impossible. METHODS: Forty eight formalin fixed, paraffin wax embedded bone marrow biopsy specimens that had been decalcified in EDTA were investigated, including 42 thought to exhibit ALL on the basis of bone marrow smears. Five specimens exhibited AML and one biphenotypic leukaemia, as diagnosed immunohistochemically in bone marrow biopsies. Immunostaining was performed with antibodies against relatively specific B and T cell antigens. The blasts were investigated for rearrangements of the immunoglobulin heavy chain (IgH) and the T cell antigen receptor (TCR) genes. RESULTS: Amplifiable DNA was obtained from all 48 specimens. An IgH gene rearrangement was detected in 20 of 23 c-ALL specimens. Four of seven T cell ALL (T-ALL) specimens had a TCR-gamma gene rearrangement, and the one B cell ALL (B-ALL) specimen exhibited a clonal IgH gene. Three of four cases of unclassifiable ALL could be assigned to the B cell lineage on the basis of gene rearrangement analysis. Seven cases originally diagnosed in smears as ALL were rediagnosed as AML (n = 5) or biphenotypic leukaemia (n = 2) because of immunohistochemical reactivity for myeloperoxidase or lysozyme. Two of these AML cases and two of three cases of biphenotypic leukaemia exhibited a monoclonal IgH gene rearrangement. CONCLUSIONS: Acute leukaemia can be subtyped in bone marrow sections with a limited panel of antibodies suitable for use on paraffin wax embedded sections (against CD3, CD10, CD20, CD79a, myeloperoxidase, and lysozyme). In patients with ALL and a diagnostically equivocal immunophenotype, gene rearrangement analysis might indicate whether the B or T cell lineage is involved.     

Simultaneous evaluation of terminal deoxynucleotidyl transferase and myeloperoxidase in acute leukemias using an immunocytochemical method

The classification of acute leukemia is important for the selection of optimal therapy. Classification often rests on morphologic, cytochemical, and immunologic criteria, and the marker enzyme terminal deoxynucleotidyl transferase (TdT) has been considered to be a reliable indicator of lymphoblastic leukemias. Because TdT-positive cells sometimes are seen in leukemias otherwise identified as myeloblastic, the authors evaluated blasts identified as myeloid by the presence of myeloperoxidase (MPO) for the simultaneous expression of TdT. The blasts in the bone marrow aspirate or peripheral blood of unselected patients with hematologic malignancies were evaluated and 60 cases are shown. The French-American-British system and, in some patients, cytochemical and immunologic studies were used to classify the leukemias. The authors demonstrated that blasts simultaneously contained MPO and TdT in 29% of patients with acute myeloblastic leukemia and 3% of patients with acute lymphocytic leukemia (ALL). This finding supports the hypothesis that TdT is an expression of cell primitivity rather than a marker for lymphoblastic cells.     

Secondary acute myeloid leukemia in children treated for acute lymphoid leukemia

We studied the risk of the development of acute myeloid leukemia (AML) during initial remission in 733 consecutive children with acute lymphoid leukemia (ALL) who were treated with intensive chemotherapy. This complication was identified according to standard morphologic and cytochemical criteria in 13 patients 1.2 to 6 years (median, 3.0) after the diagnosis of ALL. At three years of follow-up, the cumulative risk of secondary AML during the first bone marrow remission was 1.6 percent (95 percent confidence limits, 0.7 and 3.5 percent); at six years, it was 4.7 percent (2 and 10 percent). The development of secondary AML was much more likely among patients with a T-cell than a non-T-cell immunophenotype (cumulative risk, 19.1 percent [6 and 47 percent] at six years). Sequential cytogenetic studies in 10 patients revealed entirely different karyotypes in 9, suggesting the induction of a second neoplasm. In eight of these patients, the blast cells had abnormalities of the 11q23 chromosomal region, which has been associated with malignant transformation of a pluripotential stem cell. There was no evidence of loss of DNA from chromosome 5 or 7, a karyotypic change commonly observed in cases of AML secondary to treatment with alkylating agents, irradiation, or both. We conclude that there is a substantial risk of AML in patients who receive intensive treatment for ALL, especially in those with a T-cell immunophenotype, and that 11q23 chromosomal abnormalities may be important in the pathogenesis of this complication.     

Terminal deoxynucleotidyl transferase-negative acute lymphoblastic leukemia

OBJECTIVE: Terminal deoxynucleotidyl transferase (TdT) is a useful marker in the diagnosis of acute lymphoblastic leukemia (ALL) (French-American-British [FAB] L1 and L2) and is most useful in distinguishing ALL from mature B-lymphoid neoplasms, such as Burkitt lymphoma (FAB L3) and other lymphoid malignancies. The frequency of TdT-negative ALL is not known. Here we report 3 TdT-negative ALL cases that met the criteria for T-cell ALL. DESIGN: We reviewed approximately 200 cases of ALL retrieved from the database at our institution. All cases were evaluated using Wright-Giemsa, myeloperoxidase, butyrate, and TdT staining; immunophenotyped using flow cytometry; and studied using Southern blot analyses for T-cell receptors and immunoglobulin gene rearrangement. RESULTS: All ALL cases (L1 and L2) were TdT-positive, except for 3 cases that were of early T-cell lineage. None of the 3 cases demonstrated positivity for TdT in immunofluorescence staining with polyclonal antibodies or flow cytometry with monoclonal antibodies. Flow cytometric analysis confirmed a pre-T-cell immunophenotype in all 3 cases. One of the cases showed rearrangement of a T-cell antigen receptor and immunoglobulin heavy chain (J(H)). A second case showed germline configuration of T-cell receptors, but also showed rearrangement of the J(H), despite the expression of T-cell markers only.     

Rapid immunocytochemical analysis of acute leukemias.

Immunophenotypic analysis of acute leukemias is time consuming and often requires flow cytometric analysis. A 1-hour alkaline phosphatase-labeled streptavidin-biotin immunocytochemical procedure was evaluated as an alternative. Seventeen cases of acute leukemia, including 10 acute lymphocytic (ALL) and 7 acute nonlymphocytic, were phenotyped by the rapid immunocytochemical procedure and the results were compared with standard analyses. In all 17 cases, the diagnoses made using standard cytochemical and immunologic methods were the same as obtained in blinded reviews by rapid immunocytochemical analysis. Nine cases of precursor B-cell ALL were positive for CD19 and/or CD22. Five CD19 + cases of ALL reacted with anti-myeloperoxidase, with one case also positive for CD15. CD15 positivity was confirmed on repeated study as well as with plastic section immunoperoxidase staining. Nine cases of ALL were positive for CD10 and eight were positive for terminal deoxynucleotidyl transferase. One case of ALL marked as T-cell ALL with CD1, CD2, CD3, and CD7. All cases of acute nonlymphocytic leukemia were positive for CD15, CD13, and/or CD33; anti-myeloperoxidase was positive in all but one case of monocytic leukemia. All cases of acute nonlymphocytic leukemia were negative for CD10 and one was positive for terminal deoxynucleotidyl transferase. Acute leukemias apparently may be phenotyped easily and accurately in 1 hour with this immunocytochemical technique, and slides may be stored permanently for review. There was in these 17 cases high correlation of the diagnoses with standard flow cytometric and cytochemical results. This rapid method allows a coordinated evaluation of morphologic features and immunophenotype; the latter features facilitated confirmation of unexpected reactivity of myeloid markers CD15 and MPO-7 in some cases of ALL.     

CD117在急性白血病中的表达及临床意义

目的探讨CD117在急性白血病中的表达及其临床意义。方法应用CD45/SSC设门,直接荧光标记法,经流式细胞术对73例急性髓系白血病（AML）和47例急性淋巴细胞白血病（ALL）进行CD117的检测。结果对照组、ALL及AML3组CD117的表达阳性率差异有统计学意义（χ2=41.681,P﹤0.01）。AML组CD117的表达阳性率（58.9%）明显高于对照组（0）及ALL组（8.5%）。CD117/CD34的共表达率ALL组明显低于AML组（4.3%vs45.2%,P﹤0.05）。AML组CD117＋患者的CR率为60.5%,CD117-患者为76.7%,两者比较差异无统计学意义（P〉0.05）;而CD117＋/CD34＋患者的CR率为54.5%,明显低于CD117-/CD34-患者的CR率（88.2%,P﹤0.05）。结论 CD117可作为辅助诊断AML的髓系标志抗原,CD34＋/CD117＋可作为进一步排除ALL的指标。CD117＋/CD34＋可能是AML中一类预后不良的特殊亚型,可以作为AML预后判断的指标之一。     

Comprehensive flow cytometry phenotype in acute leukemia at diagnosis and at relapse

Li X, Du W, Liu W, Li X, Li H, Huang S‐A. Comprehensive flow cytometry phenotype in acute leukemia at diagnostic and at relapse. APMIS 2010; 118: 353–59. Multiparameter flow cytometry (MFC) plays a vital role in the detection of minimal residual disease (MRD) and diagnosis of relapse in acute leukemia. However, application of a limited panel of antibodies in MFC leads to high rates of false‐negative and false‐positive results. Thirteen patients with acute lymphoblastic leukemia (ALL) and 12 patients with acute myeloid leukemia (AML) were immunophenotyped by MFC at diagnosis and at relapse using a comprehensive panel of monoclonal antibodies (McAbs) to 27 antigens and CD45/SSC gating. In 23 of 25 patients (92.3%), changes in at least one of progenitor‐associated, myeloid and lymphoid antigens between diagnosis and relapse were observed. Antigen changes were observed in 92 of 239 antigens (38.5%) expressed in 25 patients, in 49 of 117 antigens (41.9%) expressed in 13 ALL patients, and in 43 of 122 antigens (35.2%) expressed in 12 AML patients. Phenotypic changes were characterized by the expression of cross‐lineage antigens. The intralineage change was observed in the majority of patients. However, myeloid lineage shift was identified by MFC in two patients with T‐ALL. Multiple panels of three or more McAbs are likely to be required in the monitoring of MRD and diagnosis of relapse in acute leukemia by MFC.     

伴骨髓增生异常相关改变的急性髓细胞白血病的免疫表型及临床特征

目的分析伴骨髓增生异常相关改变的急性髓细胞白血病(AML-MRC)的白血病相关免疫表型(LAIP)及临床特征。方法对117例初治AML患者进行重新WHO分型诊断,分析其中37例AML-MRC患者发病时经流式细胞术(FCM)检测的免疫表型结果,以45例非特殊类型AML(AML-NOS)患者为对照组。并对两组患者的发病年龄、骨髓原始细胞比例、WBC、Hb、PLT、染色体核型以及诱导化疗疗效进行比较。结果 AML-MRC组与AML-NOS组比较,其白血病相关免疫表型阳性检出率高。AML-MRC组患者骨髓原始细胞比例(40.6%vs.54.8%,P0.01)及WBC计数(19.2×109/L vs.49.2×109/L,P0.01)较AML-NOS组患者低,不良预后核型比例高(28.0%vs.0%,P0.01),CR率明显减低(22.7%vs.69.7%,P0.01)。结论 AML-MRC做为WHO新定义的一种类型,具有易于表达白血病相关免疫表型、不良预后核型比例高、常规化疗疗效不佳等特点。     

Acute Lymphoblastic Leukemia,FAB-L3, with t(8;14) and Precursor B Cell Immunophenotype: Case Report and Literature Review

Abstract

Acute lymphoblastic leukemia, FAB L3 subtype (ALL-L3), is uncommon, accounting for less than 2% of cases of ALL. It is usually associated with an unfavorable prognosis. Immunophenotypically, ALL-L3 is typically a leukemia of B cells, expressing monotypic surface immunoglobulin and B cell surface antigens, shows variable expression of CDlO (CALLA), but lacks terminal deoxynucleotidyl transferase (TdT). ALL-L3, like Burkitt's lymphoma (small non-cleaved lymphoma), is usually associated with specific chromosomal translocations, most commonly t(8;14). The authors report an unusual case of ALL-L3 with a complex karyotype including t(8;14) and the unusual finding of a precursor B cell immunophenotype with both CDlO and TdT positivity. We also review the literature for similar immunophenotypic variants of ALL with L3 morphology. (The J Histotechnol 18:149, 1995)     

Utility of white blood cell suspect flags and histogram pattern in the detection of acute leukemia by Advia-60 automated hematology analyzer

Blood samples from patients with acute leukemia, when analyzed with automated hematology counters, tend to introduce inaccuracies in the automated differential count and can cause diagnostic confusion without providing definite clues to the presence of abnormal cells. We designed this study to assess the utility of white blood cell (WBC) flags and histogram pattern generated by Advia-60 automated hematology analyzer in the recognition and categorization of acute leukemia. Data printouts of 31 newly diagnosed cases of acute leukemia, 22 with acute myeloid leukemia (AML) and 9 with acute lymphoblastic leukemia (ALL) were reviewed. All cases of AML and ALL generated the WBC suspect blastflag M2 associated with two of the non blast suspectflags G1 and G2. Among the cases of AML, 95.5% of the WBC histogram patterns were definitive of the presence of abnormal cells and were indicative of the myeloid nature of cells. Only 44.4% of the histograms in the cases of ALL could be definitive of the presence of abnormal cells and 33.3% were indicative of their lymphoid nature. Significantly, 55.5% of the histograms in ALL were normal. The false positives for both AML and ALL were 10.5% when only WBC flagging was considered and were reduced to 0.05% when the flags were combined with histogram patterns for interpretation. Combined flagging and histogram recognition can be of aid in identifying cases of acute leukemia and the morphologist can then assess these samples further. This ensures that cases of acute leukemia, especially in high output laboratories, are not inadvertently missed.     

Terminal deoxynucleotidyl transferase (TdT) in acute nonlymphocytic leukemia. A clinical, morphologic, cytochemical, immunologic, and ultrastructural study

The classification of acute leukemia is essential for proper therapy and may be based on morphologic, cytochemical, immunologic, or even ultrastructural studies. Terminal deoxynucleotidyl transferase (TdT) is expressed in most patients with acute lymphocytic leukemia (ALL) and a minority of patients with acute nonlymphocytic leukemia (ANLL). Thirteen patients with ANLL and greater than 30% blasts positive for TdT were studied to establish the clinical, light microscopic, cytochemical, immunologic, and ultrastructural correlates of this phenomenon. Most patients demonstrated some morphologic and cytochemical features of monocytic differentiation. On cytochemical stains, nine had greater than 3% Sudan black-positive blasts. Diffuse alpha naphthyl acetate esterase (ANAE) staining of leukemic cells was present in nine cases, though extremely weak in seven. Blasts in ten patients did not express any other markers of lymphoid differentiation except TdT. However, two patient's immature cells bore CD10 common ALL antigen (CALLA) and CD19 (B4). Ultrastructural studies confirmed nonlymphoid differentiation in all ten patients studied, with a prominent monocytic component present in nine. In no case was a second population of lymphoblasts identified to account for TdT positivity. These patients responded poorly to conventional therapy for ANLL, with complete remissions in 3 of 13 (23%). With conventional therapy for ALL, complete remission was achieved in only two of nine (22%) patients. However, four of seven (57%) patients had a complete remission with high-dose cytosine arabinoside regimens. The authors' studies suggest that patients with TdT-positive ANLL represent a distinct subset that usually displays ultrastructural evidence for monocytic differentiation and is clinically significant in that these patients respond poorly to conventional therapy for both ALL and ANLL. Recognition of the monocytic lineage of these cases by light microscopic examination is difficult because they are often poorly differentiated morphologically and express only weak nonspecific esterase positivity.