Colony-stimulating Factor 3 Receptor Mutated Chronic Neutrophilic Leukemia: A Rare Case Report.

Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative neoplasm, which is characterized by sustained peripheral leukocytosis with neutrophilia, hepatosplenomegaly, and hypercellularity of the bone marrow, with less than 5% myeloblasts along with normal neutrophil maturation and no dysplasia. In 2016, World Health Organization (WHO) included activating mutations in the gene for colony-stimulating factor 3 receptor (CSF3R) as one of the diagnostic criteria with CSF3RT618I being the most common mutation. We report a rare case of CNL (JAK2V617F negative, BCR-ABL1 negative, CSF3RT618I positive) in an elderly female who had an aggressive clinical course of the disease.