ABSTRACT
Chronic neutrophilic leukemia (CNL) is a rare myeloproliferative disorder characterized by clonal proliferation of mature neutrophils, hepatosplenomegaly, elevated leukocyte alkaline phosphatase score (ALP score) and a negative Philadelphia chromosome. To date, approximately 150 cases have been reported in the literature, including some cases presenting with a 'leukemic' state reflected by a neutrophilic reaction. The term 'true' CNL, recently introduced by Reilly, highlights the need for more experience with CNL cases to improve the diagnostic criteria. In Korea, about 10 cases have been reported in the literature and some of those cases did not meet the WHO diagnostic criteria for CNL. We present a typical case of CNL in a 66-year-old man who complained of general weakness and weight loss. On admission, the white blood cell count from the peripheral blood was 175,600/L with 80% segmented neutrophils. The cytogenic study was negative for the Philadelphia chromosome and had a normal karyotype.