Immunological and ultrastructural studies in acute biphenotypic leukaemia

Clinical characteristics and outcomes of mixed phenotype acute leukemia with Philadelphia chromosome positive and/or bcr-abl positive in adult

Knowledge of mixed phenotype acute leukemia (MPAL) with t(9;22)(q34;q11.2) and/or bcr-abl (Ph-positive MPAL) is limited. In this report, we review 21 adult patients with Ph-positive and/or bcr-abl positive MPAL. They were predominantly male, and presented with high WBC counts; 61.9% patients had WBC counts higher than 30 × 10(9)/L, and 33.3% patients had WBC counts higher than 100 × 10(9)/L. Electron microscopy (EM)-determined positivity for myeloperoxidase (MPO) should be considered for the classification of acute leukemia because MPO was positive by EM and flow cytometry only in 14.3% of cases in our study. Six cases (30.0%) had additional chromosome aberrations. Expression of p190(bcr-abl) was more common than that of p210(bcr-abl). There was no difference in characteristics between the p190(bcr-abl) positive and p210(bcr-abl) positive groups. The overall complete remission (CR) rate was 81.0%. Females, and patients with high WBC (>100 × 10(9)/L) at baseline had lower CR rate (57.1, 57.1%, respectively). The treatment outcome of Ph-positive MPAL is poor; the 1-year overall survival (OS) and relapse-free survival (RFS) rate were 28.0 and 18.0%, respectively. Imatinib and allogeneic hematopoietic stem cell transplantation can improve survival with Ph-positive MPAL.

Spinal cord compression as the initial presentation of acute biphenotypic leukaemia

Acute biphenotypic leukaemia (BAL) is an uncommon haematological malignancy with features of myeloid and lymphoid origin and poor overall prognosis. We report a 68-year-old man who presented with rapidly progressive upper thoracic spinal cord compression secondary to an extradural lesion. A T2-3 decompressive laminectomy with tumour excision was performed. Histopathology confirmed the diagnosis of acute biphenotypic (B/myeloid) leukaemia. The patient had only minor post-operative improvement in pyramidal lower limb weakness. He succumbed to the disease three months post-diagnosis after failing induction chemotherapy. While central nervous system involvement with acute leukaemia is well recognised, this is the first reported patient with spinal cord compression secondary to this leukaemia subtype.

Clinical characteristics and outcome of children with biphenotypic acute leukemia

BACKGROUND

Knowledge concerning the clinical and biological presentation, as well as the outcome of treatment, of biphenotypic acute leukemia in children is limited.

DESIGN AND METHODS

This retrospective review analyzes the clinical features and outcome of children with biphenotypic acute leukemia diagnosed and treated over an 8-year period. According to the EGIL scoring system 24 (3.7%) of 633 patients with acute leukemia were classified as having biphenotypic acute leukemia. The diagnostic work-up and results were reviewed specifically for this study in the light of the newly published WHO criteria for the diagnosis of leukemia of ambiguous lineage. Based on these criteria, 11 (1.7%) patients were categorized according to the new nomenclature as having mixed phenotype acute leukemia. The majority of the patients (58.3%) had a B-lymphoid/myeloid phenotype, followed by the T-lymphoid/myeloid phenotype. The most frequent chromosomal abnormality involved the 14q32 locus. Patients received therapy based on a treatment regimen for acute lymphocytic leukemia regimen, which included myeloid-effective agents.

RESULTS

At a median follow up of 4 years (range, 6 month - 7 years) the overall survival rate was 75.7% and the event-free survival rate was 73.5%. The survival of those patients who underwent hematopoietic stem cell transplantation in first complete remission was not different from that of the patients who were treated with chemotherapy alone (overall survival: 70.1% versus 81.1%, respectively, p=0.39; event-free survival: 70.1% versus 76.2%, respectively, p=0.75). The outcome of the 11 patients who were retrospectively classified as having mixed phenotype acute leukemia according to the new WHO criteria was excellent, with no relapses or deaths occurring among these patients.

CONCLUSIONS

An acute lymphocytic leukemia type of induction therapy, using agents that are active against lymphoid and myeloid leukemias, appears to be more effective in achieving and maintaining complete remissions regardless of whether the patients are classified according to EGIL criteria or the new WHO criteria. Hematopoietic stem cell transplantation may not be necessary for all patients in first complete remission.

Cytogenetics, molecular and ultrastructural characteristics of biphenotypic acute leukemia identified by the EGIL scoring system

Biphenotypic acute leukemia (BAL) is a rare, difficult to diagnose entity. Its identification is important for risk stratification in acute leukemia (AL). The scoring proposal of the European Group for the Classification of Acute Leukemia (EGIL) is useful for this purpose, but its performance against objective benchmarks is unclear. Using the EGIL system, we identified 23 (3.4%) BAL from among 676 newly diagnosed AL patients. Mixed, small and large blast cells predominated, with FAB M2 and L1 constituting the majority. All patients were positive for myeloid (M) markers and either B cell (B) (17 or 74%) or T cell (T) (8 or 34%) markers with two exceptional patients demonstrating trilineage phenotype. Six (50%) of studied M-B cases were positive for both IGH and TCR. In six (26%) patients myeloid lineage commitment was also demonstrable by electron cytochemistry. Abnormal findings were present in 19 (83%) patients by cytogenetics/FISH/molecular analysis as follows: t(9;22) (17%); MLL gene rearrangement (26%); deletion(6q) (13%); 12p11.2 (9%); numerical abnormalities (13%), and three (13%) new, previously unreported translocations t(X;6)(p22.3;q21); t(2;6)(q37;p21.3); and t(8;14)(p21;q32). In conclusion, the EGIL criteria for BAL appear robust when compared against molecular techniques that, if applied routinely, could aid in detecting BAL and help in risk stratification.

Minimally Differentiated Acute Myeloid Leukemia (AML-M0): Comparison of 25 Cases With Other French-American-British Subtypes

We compared the immunophenotypic and karyotypic features of 25 cases of minimally differentiated acute myeloid leukemia (AML-M0) with those of 247 cases comprising all AML French-American-British (FAB) classification. Myeloperoxidase (MPO) was detectable with a specific monoclonal antibody in all cases of AML-M0, whereas CD13 and CD33 were both negative in 4 of the 25 cases. Thus, anti-MPO reliably detects minimal myeloid differentiation in AML-M0. CD34 and terminal deoxynucleotidyl transferase (TdT) were more frequently expressed in AML-M0 (96% and 68% of the cases, respectively) than in the other FAB subsets (P < . 001 for both). By contrast, GP-170 and CD7 were less frequently expressed in AML-M0 than in FAB classes such as M1, M4, and M5 (P = .02 and .003, respectively). A total of 80% of AML-M0 cases carried lymphoid markers (including TdT), and 48% showed a coordinate positivity for two or more of them. CD2, CD5, CD10, and CD19 were expressed in a similar fashion among the different FAB groups, whereas CD4 expression was significantly more frequent in AML-M0, AML-M4, and AML-M5 (P = .014). AML-M0 was characterized by a more frequent occurrence of complex karyotypes. In addition, approximately 20% of cases had TdT positivity, complex karyotypes, and anomalies of chromosome 5 and/or 7, a pattern not observed in the other FAB subsets. Finally, 80% of anomalies of chromosome 5 and/or 7 in AML-M0 were comprised within complex karyotypes, whereas only 13% of the remaining FAB cases carried this feature. In summary, AML-M0 frequently expresses immunophenotypic and karyotypic aspects that are likely to identify a “stem cell” pattern.