Atypical chronic myeloid leukemia

A rare myelodysplastic/myeloproliferative neoplasm characterized by peripheral blood leukocytosis due to increased numbers of morphologically dysplastic neutrophils and their precursors, hypercellular bone marrow with granulocytic proliferation and dysplasia (with or without dysplasia in the erythroid and megakaryocytic lineages), and prominent dysgranulopoiesis, but no or minimal absolute basophilia or monocytosis. Blasts account for less than 20% of leukocytes in the blood and bone marrow. BCR-ABL1 fusion is absent, as well as PDGFRA, PDGFRB or FGFR1 rearrangement, or PCM1-JAK2. Patients may present with signs and symptoms related to splenomegaly, anemia, or thrombocytopenia. Prognosis is generally poor.