Lineage switch from acute myeloid leukemia to biphenotypic acute leukemia with acquisition of Philadelphia chromosome

Myeloid Blast Crisis of Chronic Myeloid Leukemia Followed by Lineage Switch to B-Lymphoblastic Leukemia: A Case Report

Lineage switch is very rare in blastic crisis of chronic myeloid leukemia (CML-BC). Here, we report a case of CML-BC in which the blast lineage switched from myeloid to B-lymphoid. A 35-year-old male was initially admitted to our hospital because of abdominal distention for over a year and dizziness for one week. Prior to presentation at our hospital, he visited a local hospital because of abdominal distention where his white blood cell count and bone marrow (BM) smear indicated CML. Results from peripheral blood (PB) counts, bone marrow analysis, immunophenotyping by flow cytometry, and the detection of the Philadelphia chromosome were consistent with a diagnosis of myeloid blast crisis from CML. The patient received chemotherapy with imatinib for induction, which diminished the number of blasts. However, after three months, the blasts were increased in the PB and BM. The BM study and immunophenotyping by flow cytometry revealed B-lymphoblastic leukemia. In accordance with his first admission, a chromosome study revealed a karyotype of 46, XY, t(9; 22)(q34; q11) in all 20 cells analyzed, and B-lymphoblastic transformation from CML was diagnosed. Despite three months of treatment with DVCP (daunorubicin, vincristine, cyclophosphamide and prednisone) chemotherapy in combination with dasatinib, the patient did not achieve complete remission. The patient decided to stop treatment and was discharged from the hospital for financial reasons. This case implicates the Philadelphia chromosome with p210 BCR-ABL1 fusion proteins as a key molecule in CML-BC. Further research is needed to assess the frequency, treatment, and prognosis of CML-BC patients with lineage switch.

Lineage Switch Between B-Lymphoblastic Leukemia and Acute Myeloid Leukemia Intermediated by "Occult" Myelodysplastic Neoplasm: Two Cases of Adult Patients With Evidence of Genomic Instability and Clonal Selection by Chemotherapy

OBJECTIVES

Lineage switch occurs in rare leukemias, and the mechanism is unclear. We report two cases of B-lymphoblastic leukemia (B-ALL) relapsed as acute myeloid leukemia (AML).

METHODS

Retrospective review of clinical and laboratory data.

RESULTS

Complex cytogenetic abnormalities were detected in B-ALL for both cases with subclone heterogeneity. Postchemotherapy marrow biopsies showed trilineage hematopoiesis without detectable B-ALL. Cytogenetics in both showed stemline abnormalities. The cases were considered "occult" myelodysplastic syndrome (MDS) preceding B-ALL. The patients relapsed 6.5 and 9 months following induction, respectively. Case 1 relapsed as AML-M5 initially, was treated as such, and then relapsed again as B-ALL. Case 2 relapsed as AML-M6. Cytogenetics demonstrated persistent abnormalities. Both patients died soon after relapse.

CONCLUSIONS

Lineage switch between B-ALL and AML could be intermediated by occult MDS. A pluripotent progenitor likely undergoes neoplastic transformation, resulting in a genomically unstable clone. This leads to a repertoire of heterogeneous subclones that may be selected by chemotherapy. Lineage switch heralds a dismal clinical outcome.

Unbalanced 1q whole-arm translocation resulting in der(14)t(1;14)(q11-12;p11) in myelodysplastic syndrome

Unbalanced whole-arm translocations (WATs) of the long arm of chromosome 1, resulting in complete trisomy 1q, are chromosomal abnormalities detectable in both solid tumors and hematologic neoplasms. Among the WATs of 1q to acrocentric chromosomes, a few patients with der(1;15) described as a dicentric chromosome have been reported so far, whereas cases of der(1;14) are much rarer. We report on a case of der(1;14) detected as single anomaly in a patient with myelodysplastic syndrome. The aim of our work was to investigate the breakpoints of the (1;14) translocation leading to the der(1;14). Fluorescence in situ hybridization (FISH) experiments have been performed on chromosome preparations from bone marrow aspirate, using specific centromeric probes of both chromosomes, as well as a probe mapping to 1q11 band. FISH results showed that in our patient the derivative chromosome was monocentric with a unique centromere derived from chromosome 14. The breakpoints of the translocation were located in the short arm of chromosome 14 and in the long arm of chromosome 1, between the alphoid D1Z5 and the satellite II domains. The 1q breakpoint was within the pericentromeric region of chromosome 1, which is notoriously an unstable chromosomal region, involved in different chromosomal rearrangements.

Chronic myelogenous leukemia showing biphenotypic blast crisis followed by lineage switch to B lymphoblastic leukemia

Lineage switch is a very rare event in blastic crisis of chronic myelogenous leukemia (CML-BC). To our knowledge, only three cases of lineage switch between lymphoid and myeloid/myelomonocytic lineages have been reported in the literature. Here, we report a novel case of imatinib-resistant CML-BC, in which the blast lineage switched from biphenotypic to B-lymphoid.