Two cases of Chronic Neutrophilic Leukemia were successfully treated with Allogeneic Stem Cell Transplantation

Objective: Chronic Neutrophilic Leukemia (CNL) is a rarely seen myeloproliferative neoplasia (MPN) in which the BCR-ABL1 gene mutation is negative, and is characterized by persistent neutrophilic proliferation in the bloodstream and granulocytic hyperplasia in the bone marrow. CNL is usually diagnosed incidentally in asymptomatic individuals with persistent neutrophilic leukocytosis. When genetically examined, BCR-ABL1 fusion gene, JAK-2 V617F, and exon12 mutations, CALR mutations, PDGFRA-B, FGRF1 mutations are all not detected, while CSF3R mutation is observed in most of the cases. The WHO-2016 classification determined the presence of CSF3R T618I and other activating CSF3R mutations as diagnostic criteria. While the prognosis is poor in CNL cases with the CSF3R T618I mutation, it is more moderate in the presence of other CSF3R mutations. The average life expectancy is 21-30 months, and 5-year survival rates are around 28%. Although no treatment modality provides an average survival advantage other than hematopoietic stem cell transplantation (HSCT), there is no accepted 'standard of care' consensus. HSCT procedures performed in CNL cases are limited in the literature. Case: In this study, we presented two cases of CNL who were successfully treated with allogeneic stem cell transplantation and cured.