Cytogenetics has long represented a critical component in the clinical evaluation of hematologic malignancies. Chromosome banding studies provide a simultaneous snapshot of genome-wide copy number and structural variation, which have been shown to drive tumorigenesis, define diseases, and guide treatment. Technological innovations in sequencing have ushered in our present-day clinical genomics era. With recent publications highlighting novel sequencing technologies as alternatives to conventional cytogenetic approaches, we, an international consortium of laboratory geneticists, pathologists, and oncologists, describe herein the advantages and limitations of both conventional chromosome banding and novel sequencing technologies and share our considerations on crucial next steps to implement these novel technologies in the global clinical setting for a more accurate cytogenetic evaluation, which may provide improved diagnosis and treatment management. Considering the clinical, logistic, technical, and financial implications, we provide points to consider for the global evolution of cytogenetic testing.

Myeloid/lymphoid neoplasms withFLT3gene fusions have recently been included among myeloid/lymphoid neoplasms with eosinophilia and tyrosine kinase gene fusions (MLN-TK) in the World Health Organization classification and International Consensus Classification. As this entity remains remarkably rare, its scope and phenotypic features are evolving. In this report, we describe a 33-yr-old male with MLN-TK. Conventional chromosome analysis revealed a t(13;14)(q12;q32). Further analysis with mate-pair sequencing (MPseq) confirmed aTRIP11::FLT3gene fusion. A diagnosis of MLN-TK was rendered. To the best of our knowledge, we report the third case of MLN-TK with aTRIP11::FLT3gene fusion. In contrast to previously described cases, our case exhibited distinctly mild clinical features and disease behavior, emphasizing the diverse spectrum of MLN-TK at primary presentation and variability in disease course. MLN-TK withFLT3gene fusions are a genetically defined entity which may be targetable with tyrosine kinase inhibitors with anti-FLT3 activity. Accordingly, from diagnostic and therapeutic viewpoints, genetic testing forFLT3rearrangements using fluorescence in situ hybridization (FISH) or sequencing-based assays should be pursued for patients with chronic eosinophilia.