A rare disorder characterised by neutrophilia in peripheral blood and expansion of neutrophilic granulopoiesis. The BCR-ABL1 fusion gene is absent as well as other reactive causes and MPNs.
90% of all cases show a normal genetic prophile, BCR-ABL1 is absent, however JAK 2 mutation may occasionally occure.
Hypercellular bone marrow with predominant neutrophilic granulopoiesis (M:E is 20:1 or more), the number of myeloblasts and promyelocytes is not increased, myelocytes and mature neutrophils predominate. Erythroid and megakaryocytic preliferation may occur. Significant dysplastic changes are absent.