Hematologic malignancies with PCM1-JAK2 gene fusion share characteristics with myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB, and FGFR1.

The translocation t(8;9)(p22;p24) is a rare event that results in the fusion of JAK2 to PCM1 and thus leads to the activation of the Janus Kinase 2. In 2008, the WHO introduced a new entity called "Myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB or FGFR1", which are characterized by the formation of a fusion gene encoding an aberrant tyrosine kinase. These disorders share characteristics with myeloproliferative neoplasms and typically show an eosinophilia. We here now report on 6 new cases with PCM1-JAK2 fusion. These patients show characteristics with respect to epidemiology, clinical presentation, and genetic changes that are very similar to patients with rearrangements of PDGFRA, PDGFRB, or FGFR1. Our data suggests the integration of cases with JAK2-PCM1 fusion in the respective WHO category of myeloid and lymphoid neoplasms with eosinophilia and abnormalities of PDGFRA, PDGFRB, or FGFR1.