Myeloid/lymphoid neoplasms with tyrosine kinase gene fusions (MLN-TK) represent a distinct group of hematologic malignancies recognized in the latest WHO classification due to shared clinical, morphological, and molecular features, and their responsiveness to tyrosine kinase inhibitors (TKIs). Among these, fusions involving the
SYK
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Myeloid/lymphoid neoplasms with tyrosine kinase gene fusions (MLN-TK) represent a distinct group of hematologic malignancies recognized in the latest WHO classification due to shared clinical, morphological, and molecular features, and their responsiveness to tyrosine kinase inhibitors (TKIs). Among these, fusions involving the
SYK gene, such as
ETV6::SYK and
ITK::SYK, have emerged as rare but potentially targetable genetic events in both myeloid and lymphoid neoplasms. SYK, a non-receptor tyrosine kinase critical for hematopoietic signalling, can become constitutively activated through gene fusions, driving oncogenesis via the PI3K/AKT, MAPK, and JAK-STAT pathways.
ETV6::SYK has been primarily associated with myeloid neoplasms, often presenting with eosinophilia, bone marrow dysplasia, and skin involvement. In vitro and in vivo models confirm its leukemogenic potential and identify SYK as a therapeutic target. Although SYK inhibitors like fostamatinib have shown transient efficacy, resistance mechanisms, possibly involving alternative pathway activation, remain a challenge. The
ITK::SYK fusion, on the other hand, has been identified in peripheral T-cell lymphomas, particularly of the follicular helper T-cell subtype, with similar pathway activation and potential for targeted intervention. Additional rare SYK fusions, such as
PML::SYK and
CTLC::SYK, have been reported in myeloid neoplasms and juvenile xanthogranuloma, respectively, expanding the spectrum of SYK-driven diseases. Accumulating evidence supports the inclusion of SYK fusions in future classification systems and highlights the need for broader molecular screening and clinical evaluation of SYK-targeted therapies.
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