JAK2 and myelofibrosis: Different pathogenesis mechanisms participate in transformation, including transformation of existing potential preleukemic clones, since <i>JAK2</i>-mutant myeloproliferative neoplasms often transform to <i>JAK2</i> wild-type acute myeloid leukemia.<h4>Case presentation</h4>Here, we present an 80 year old man with a <i>JAK2</i>-V617F mutant primary myelofibrosis.