Test Details: The myeloid/lymphoid neoplasms with eosinophilia and rearrangements of PDGFRA, PDGFRB, FGFR1 and JAK2 represent a significantly diverse group of hematologic malignancies. Despite the disparate clinical presentations, which include chronic myeloid neoplasms (chronic myelomonocytic leukaemia, chronic myeloproliferative neoplasms, chronic eosinophilic leukaemia) versus more acute myeloid and lymphoid neoplasms (acute myeloid leukaemia, B- and T-lymphoblastic leukaemia/lymphoma and mixed phenotypic acute leukaemias), this diagnostic subgroup shares rearrangements involving 4 specific gene regions: PDGFRA, PDGFRB, FGFR1 and JAK2.