A myeloproliferative neoplasm with translocation t(8;9)(p22;p24) involving JAK2 gene.

A 35-year-old male presented with a several-weeks history of abdominal discomfort, early satiety, low-grade fever, night sweats, and weight loss. Physical examination revealed pale skin and a massive hepatosplenomegaly. A complete blood count showed severe anemia, thrombocytopenia, and marked leukocytosis (100 000/mL) with 10% blasts, eosinophilia (4000/mL), and basophilia (3000/mL). Peripheral smear demonstrated blasts (panel A), early myeloid precursors (panels A-C), eosinophilia (panels A-C), and basophilia (panel C). Bone marrow biopsy showed myeloid lineage hyperplasia. Cytogenetic analysis was significant for t(8;9)(p22;p24). Testing for JAK2 mutation was negative, and FISH analysis failed to show BCR-ABL1 or any abnormality involving PDGFRA, PDGFRB, or FGFR1 genes. The patient was diagnosed with myeloproliferative neoplasm (MPN)-unclassified after excluding other hematologic neoplasms and causes of eosinophilia/basophilia.