Multiple chromosome abnormalities in a drug resistant TdT positive B-cell leukemia

Is B-lineage acute lymphoblastic leukemia with a mature phenotype and l1 morphology a precursor B-lymphoblastic leukemia/lymphoma or Burkitt leukemia/lymphoma?

CONTEXT

B-lineage acute lymphoblastic leukemia (ALL) with a mature phenotype and L1 morphology is a rare condition that may pose a diagnostic and management challenge.

OBJECTIVE

To report our experience with 2 such unusual cases of pediatric B-lineage ALL.

DESIGN

Morphologic, immunophenotypic, and cytogenetic features of the leukemic blast cells were reviewed in conjunction with clinical and other laboratory findings.

RESULTS

The leukemic blast cells in both cases were small to medium with scant basophilic cytoplasm and several small inconspicuous nucleoli, characteristic of L1 lymphoblasts. Immunophenotypically, they were positive for CD19, CD22, and low-density CD20, with expression of surface immunoglobulin lambda light chain. They were negative for immature (CD34 and terminal deoxynucleotidyl transferase), myeloid, and T-cell-associated markers. Conventional cytogenetic and fluorescent in situ hybridization studies failed to demonstrate chromosomal translocations involving the c-myc gene. Both patients were treated with Children's Cancer Group ALL protocols and had good responses.

CONCLUSIONS

B-lineage ALL with a mature phenotype, L1 morphology, and absent chromosomal translocations involving the c-myc gene is best classified and managed as precursor B-lymphoblastic leukemia/lymphoma instead of Burkitt leukemia/lymphoma.

Immunophenotyping of leukemia

Modern immunophenotyping of hematological malignancies by flow cytometry is assisted by a wide array of easily accessible monoclonal antibodies, by antibodies conjugated to diverse fluorochromes, and by reliable techniques for cell membrane permeabilization. Simultaneous assessment of multiple surface and intracellular markers at diagnosis reduces the number of cells required, helps the identification of the malignant cells and determines the degree of immunophenotypic heterogeneity of the malignant cell population. A few critical markers are sufficient to establish the lineage association in the majority of cases of acute and chronic leukemias and lymphomas. More extensive immunophenotyping can provide information about the cells' stage of differentiation, assess the expression of prognostically important features, and determine clonality. The identification of leukemia-associated immunophenotypes can be used for monitoring minimal residual disease during therapy. The presence of cells expressing these phenotypes in patients who are in clinical remission is associated with an increased risk of relapse.

Association of 17p loss with late-stage or refractory disease in hematologic malignancy

Twenty-five patients with loss of part or all of 17p were selected from 701 patients with hematologic malignancies karyotyped either at diagnosis and/or at relapse and/or in refractory disease. Loss of 17p resulted from partial arm deletion (eight cases), unbalanced translocation (12 cases), i(17)(q10)(five cases) or monosomy 17 (four cases). In three cases, both 17ps were missing; in one case, two sublines independently acquired loss of 17p. In eight cases, loss of 17p was confirmed as a secondary change. The karyotypes generally were complex, with an average of 4.0 structurally abnormal chromosomes in the simplest lines showing 17p loss. The incidence at diagnosis was acute lymphoblastic leukemia (ALL) 2.2%, acute myeloid leukemia (AML) 2.4%, and myelodysplastic syndrome (MDS) 3.4%. The incidence in relapse and refractory disease was ALL 8.9%, AML 3.3%, and MDS 6.3%. The increased incidence of 17p loss in relapse and refractory disease was statistically significant (p < 0.05). Loss of 17p appears to be a feature of late-stage or resistant disease in hematologic malignancy.

Chromosomal abnormalities in adult non-endemic Burkitt's lymphoma and leukemia: 22 new reports and a review of 148 cases from the literature

Tumour cell karyotypes from patients with Burkitt lymphoma (BL) or Burkitt's type leukemia (ALL3) were studied for correlation with survival, bone marrow and cerebral spinal fluid involvement (CSF), human immunodeficiency virus (HIV) serology, and for recurrent cytogenetic abnormalities. The records of 22 patients with BL from our institution and of 148 cases of BL and ALL3 reported in the literature with karyotypes were evaluated for clinical and cytological features. Overall survival was only 28 per cent and 88 per cent of deaths occurred within the first nine months after diagnosis. Those who survived at least 18 months were unlikely to relapse. Age and gender did not significantly affect survival. Patients presenting with advanced Ann Arbor stage, bone marrow or CSF involvement had lower survival rates. The association of translocations involving chromosome band 8q24 with this disease is confirmed. Sixty-two per cent of karyotypes had t(8;14)(q24;q32) translocations; the recognized variant translocations t(8;22)(q24;q11) and t(2;8)(p12;q24) affected 12 per cent and 9 per cent respectively. Seventeen per cent had abnormal karyotypes but no classic translocation. Patients with variant translocations had the poorest survival rates, and those with the classic t(8;14)(q24;q32) did the best. Despite a small sample size, the variant translocation t(8;22)(q24;q11) appeared to occur at an increased frequency in the patients with AIDS. In the entire group, recurrent involvement of chromosome regions 1q2, 6q11-14 and 17p1 suggests that alteration of genes at these loci, B Cell Growth Factor (BCGF) at 1q2 and p53 on 17p, may contribute to the development and progression of this tumour. Similarly, the frequent trisomies of chromosomes 7, 8, 12 and 18 may indicate an effect on tumour cell growth due to increased gene dosage. Trisomy 12 was found in eight tumours, five from patients with AIDS, suggesting that chromosome 12 has a site or gene whose allelic dosage is selected for in AIDS related lymphoma cells. Cytogenetic studies of adult Burkitt lymphoma and leukemia suggest several likely loci for gene alterations that in conjunction with myc translocations can lead to tumorigenesis.

del(2)(p23): a new recurrent abnormality in acute myeloid leukemia

In two patients with acute myeloid leukemia, we found a new chromosome abnormality: del(2)(p23) which was detected in 13% and 50% of studied bone marrow cells, respectively. In patient one, del(2p) was an additional abnormality to t(8;21), while patient two had del(2p) as the sole abnormality. Based on our observation and a review of the literature we propose that del(2p) is a new recurrent chromosome abnormality for acute myeloid leukemia.

Sequential karyotypes in non-Hodgkin lymphoma: their nature and significance

The examination of sequential karyotypes in hematologic disorders has demonstrated that karyotypic changes are often associated with concurrent changes in clinical behavior. Acquired abnormalities that recur among different patients may also suggest genomic areas important to tumor progression. We therefore examined sequential karyotypes in 21 patients with non-Hodgkin lymphoma (NHL). Sixteen of the 21 karyotypes demonstrated changes, including the majority of 6 small lymphocytic, 11 follicular, and 4 intermediate and high-grade diffuse lymphomas. The t(14;18)(q32;q21) occurred in ten initial karyotypes was retained in all cases. The band most frequently affected by newly acquired abnormalities was 14q32 (n = 5); chromosomes 1 and 2 (n = 5, each), and the 17p arm (n = 4) were also commonly affected. The acquired deletion of all or part of 17p appeared to be associated with a poor prognosis. Histologic transformation and karyotypic change did not correlate. This study of sequential karyotypes in NHL 1) confirms the primary importance of the t(14;18), 2) suggests that the 14q32 band is involved frequently in both primary and secondary cytogenetic events, and 3) suggests other genomic regions of potential significance to progression.

TdT positive B-cell acute lymphoblastic leukaemia (B-ALL) without Burkitt characteristics

The leukaemic cells in a 23-year-old man were small to medium-sized lymphoblasts with no cytoplasmic vacuoles and negative with PAS as well with peroxidase and acid phosphatase staining. Cytogenetic analysis showed -6, +12, -22, +mar (6p::22q), resulting in a trisomy 12 and monosomy of the long arm of chromosome 6. Immunological marker analysis revealed that the majority of the blasts was positive for terminal deoxynucleotidyl transferase (TdT) as well as surface membrane immunoglobulin (SmIg, mu, lambda), although B-ALL are supposed to be negative for TdT. The blasts were also positive for HLA-DR, CD9 (BA-2), CD10 (VIL-A1) and CD24 (BA-1), but negative for the B-cell markers CD20 (B1) and Y29/55. Double immunofluorescence staining confirmed that almost all TdT+ cells were also positive for Sm mu, Sm lambda, HLA-DR and CD10. We thus made a diagnosis of TdT+ B-ALL without Burkitt characteristics. Since we could not detect SmIg+/TdT+ cells in bone marrow samples from adult healthy volunteers and from 10 children with ALL in complete remission, we conclude that TdT+ B-ALL cells may not have a normal counterpart in bone marrow or represent a malignant counterpart of a very rare cell in an intermediate differentiation stage between the pre-B-cell and the early B lymphocyte.