Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative neoplasm that features a persistent neutrophilia in peripheral blood, myeloid hyperplasia in bone marrow, hepatosplenomegaly, and the absence of the Philadelphia chromosome or a BCR/ABL fusion gene.
[5] However, a clonal genetic abnormality has not been detected in these myeloma-associated cases of CNL, raising the possibility that the neutrophilia is a reaction due to the neoplastic myeloma cells.
[2] Peripheral blood neutrophilia (> 25 x 109/L) with myeloid precursors (promyelocytes, myelocytes, metamyelocytes) comprising less than 5% of leukocytes.
[3][4] Peripheral blood, bone marrow, spleen, and liver are most common, but any organ or tissue can be infiltrated by neutrophils.
Due to the myeloproliferative nature of the disease, an increase in megakaryocytes and erythroid precursors may be observed, but dyspoiesis in not seen in any cell lineage.