A 30-year-old man with
chronic neutrophilic leukemia (CNL) in association with
monoclonal gammopathy is presented. Physical examination on admission revealed moderate hepatosplenomegaly. Initial blood count showed neutrophilic
leukocytosis (42.2 x 10(9)/1 with 90% mature neutrophils). Leukocyte
alkaline phosphatase (LAP) score was elevated. Bone marrow aspiration showed myeloid
hyperplasia without dysplastic features. Karyotypic and molecular analyses of bone marrow cells showed the absence of Philadelphia (
Ph1) chromosome and bcr gene rearrangement. Because there was no underlying
infection or
neoplasm, he was diagnosed as having CNL associated with
IgG kappa-type
monoclonal gammopathy (
IgG, 1,269 mg/dl). In addition to its association with
monoclonal gammopathy of undetermined significance (MGUS), the present case was also characterized by spontaneous remission of CNL during the 12-year follow-up, accompanied by a gradual increase in serum
IgG levels up to 3,000 mg/dl. As far as we know, there have been 19 cases of CNL associated with
monoclonal gammopathy in the literature. The median survival of these cases was 5 years. Although there have been only 6 cases of CNL associated with MGUS, survival of these cases was particularly favorable. Taken together with the observation that
leukocytosis and hepatosplenomegaly in the present case subsided without specific treatment, we speculate that myeloid proliferation in the present case may have been a
leukemoid reaction to underlying
monoclonal gammopathy.