Chronic myeloid leukemia (CML) is a myeloproliferative neoplasm the hallmark of which, the breakpoint cluster region-Abelson (BCR-ABL) oncogene, has been the target of tyrosine kinase inhibitors (TKIs), which have significantly improved the survival of patients with CML.
The objective of this review is to characterize studies on BCR-ABL1-negative chronic myeloproliferative neoplasms and to compare the frequency of JAK2, MPL and CALR mutations in PV, ET and PMF.
The hallmark of <i>BCR-ABL1</i>-negative myeloproliferative neoplasms (MPNs) is the presence of a driver mutation in <i>JAK2, CALR</i>, or <i>MPL</i> gene.
Four patients presented with B-lymphoblastic leukemia (B-ALL), and of them, two patients with t(8;9)(p22;p24.1) were proven to be B-lymphoblastic crisis of MPN; and the other two cases with t(9p24;v) both were de novo B-ALL, BCR-ABL1-like (Ph-like).
Key genetic aberrations include the BCR-ABL1 gene rearrangement in Philadelphia chromosome-positive chronic myelogenous leukemia (CML) and JAK2/MPL/CALR aberrations in Philadelphia chromosome-negative MPNs.
Although BCR-ABL1-negative myeloproliferative neoplasms (MPN) are chronic, clonal hematopoietic stem cell (HSC) disorders marked by proliferation of one or more myeloid lineages, a substantial proportion of patients transform to acute myeloid leukemia.
BCR-ABL1-negative myeloproliferative neoplasms (MPNs) are clonal stem cell disorders defined by proliferation of one or more myeloid lineages, and carry an increased risk of vascular events and progression to myelofibrosis and leukemia.
The combination of laboratory testing for the detection of JAK2, CALR, and MPL mutations is necessary to improve the diagnosis and classification of BCR-ABL1-negative MPN.
For patients with MPNs, detection of the <i>BCR-ABL1</i> fusion delineates chronic myeloid leukemia from classic <i>BCR-ABL1</i><sup>-</sup> MPNs, which are largely defined by mutations in <i>JAK2</i>, <i>CALR</i>, or <i>MPL</i> In the B-cell lymphomas, detection of characteristic rearrangements involving <i>MYC</i> in Burkitt lymphoma, <i>BCL2</i> in follicular lymphoma, and <i>MYC/BCL2/BCL6</i> in high-grade B-cell lymphomas are essential for diagnosis.
In summary, most patients with chronic eosinophilic leukemia, not otherwise specified and a proportion of those with idiopathic hypereosinophilic syndrome show abnormal bone marrow features similar to the ones encountered in patients with myelodysplastic syndromes, myelodysplastic/myeloproliferative neoplasm or <i>BCR-ABL1</i>-negative myeloproliferative neoplasm.
The classical BCR-ABL1-negative myeloproliferative neoplasms (MPN) include primary myelofibrosis (PMF), polycythemia vera (PV) and essential thrombocythemia (ET).
Atypical chronic myeloid leukemia, <i>BCR-ABL1</i> negative (aCML) is a rare myelodysplastic syndrome (MDS)/myeloproliferative neoplasm (MPN) for which no current standard of care exists.
Hence, we examined a cohort of 123 myeloproliferative neoplasm (MPN) patients without BCR-ABL1 rearrangement and additional ET patients (n=96) for coexistence of JAK2 and CALR mutations.
This brief review summarizes the current guidelines as they apply to diagnosing both the classical BCR-ABL1 negative MPN (polycythemia vera, essential thrombocythemia, and primary myelofibrosis) and the more common subtypes of MDS/MPN overlap syndromes.