LAUSR

BackgroundChronic neutrophilic leukemia (CNL) is a rare myeloproliferative neoplasm (MPN) with less than 40 cases of patients being reported or clinically suspected meeting with 2008 World Health Organization (“WHO”) diagnostic criteria. The current diagnosis of CNL remains to exclude other diseases. Recently, a new biomarker of CSF3R mutations that is almost invariably present in CNL has been identified. There is no effective treatment for CNL, therefore prognosis of the disease is poor, but it may be attributed to the presence of both SETBP1 and CSF3R gene mutations. The presence or absence of CSF3R mutation did not affect survival, whereas a trend for shortened survival was observed among patients with SETBP1-mutation.Case presentationHere we report a 65-year old woman patient who presented with leukocytosis without sign of fever and tumors. Bone marrow aspirates showed a markedly hypercellular feature with 76%–92% myeloid and the dysplastic changes were found in about 7% of neutrophils cells. The bone marrow biopsy demonstrated marrow fibrosis with Gomori staining positive (+++~++++). Cytogenetic analysis showed 46,X,del (X) (q22). No molecular markers of BCR/ABL1 rearrangement (P210, P230, P190 and variably), JAK2V617F, FIP1L1-PDGFRA, TEL-PDGFRB, ZNF198-FGFR1 and SETBP1 mutations were identified, however, the CSF3R gene membrane proximal mutation (c.1853C > T/p.T618I sites) was detected by PCR techniques. The patient was diagnosed with CNL and died in about 2 months after disease diagnosis.ConclusionIn clinical course, the CNL concurrently with severe bone marrow fibrosis and dysplastic features as well as X chromosomal abnormality may predict a worsening prognosis regardless of SETBP1 mutation status.