Lab Med Online.  2017 Oct;7(4):206-210. 10.3343/lmo.2017.7.4.206.

Neutrophilic Leukemoid Reaction Associated with Malignancy Initially Suspected as Chronic Neutrophilic Leukemia

  • 1Department of Laboratory Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
  • 2Department of Internal Medicine, Ewha Womans University School of Medicine, Seoul, Korea.
  • 3Department of Laboratory Medicine, Dongguk University, Ilsan Hospital, Goyang, Korea.


Although neutrophilia can manifest from various causes, it is important to be able to distinguish chronic neutrophilic leukemia (CNL) from neutrophilic leukemoid reactions (NLR). In this paper, we describe four cases of leukocytosis with neutrophilia, including one case of CNL with a T618I mutation in colony stimulating factor 3 receptor (CSF3R) and three cases of NLR associated with malignancy or sepsis, which were initially suspected as CNL. Of the three NLR cases, one was associated with ovarian cancer, one with monoclonal gammopathy of undetermined significance and one with multiple myeloma with sepsis. This study demonstrated that confirming the clonality of myeloid cells with CSF3R T618I could contribute to making an accurate differential diagnosis between CNL and NLR in patients with solid cancers or plasma cell neoplasms caused by paraneoplastic syndromes and/or infection.


Chronic neutrophilic leukemia; Neutrophilic leukemoid reaction; Colony stimulating factor 3 receptor; Paraneoplastic syndrome; Plasma cell neoplasm
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