We show that the hematopoietic neoplasms with 9p24/JAK2 rearrangement are extremely rare, and most of them are associated with t(8;9)(p22;p24)/PCM1-JAK2, a recent provisional World Health Organization entity under "myeloid/lymphoid neoplasm with a specific gene rearrangement".
Janus kinase 2 (JAK2) is a central kinase in hematopoietic stem/progenitor cells (HSPCs), and its uncontrolled activation is a prominent oncogenic driver of hematopoietic neoplasms.
The 2016 World Health Organization (2016 WHO) classification of hematopoietic malignancies classifies neoplasms with a fusion between the FIP1L1 and PDGFRA genes in 4q12 into a group called "myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB or FGFR1 or with PCM1-JAK2".
JAK2-positive cutaneous myelofibrosis presenting as sclerosing extramedullary hematopoietic tumors on the scalp: case presentation and review of the literature.
Although certain molecular defects are indicative of distinct cytogenetic abnormalities, others represent point mutations in critical target genes (RUNX1, N-RAS, JAK2, KIT, others) and sometimes are associated with a particular type of MDS, an overlap disease, a co-existing hematopoietic neoplasm or disease progression.
This finding adds to the expanding compendium of JAK2 aberrations found in various hematopoietic malignancies, as well as the potential need for a diagnostic FISH analysis in the appropriate clinical setting.
Recent studies have implicated de-regulation of Jak2 kinase activity by chromosomal translocations in hematopoietic tumors and mutations within the pseudokinase domain in a spectrum of myeloproliferative diseases.
Activation of JAK2 by chromosomal translocation or point mutation is a recurrent event in hematopoietic malignancies, including acute leukemias and myeloproliferative disorders.