Multiple myeloma coexisting colon carcinoma as the presenting symptom of a neutrophilic leukemoid reaction: a rare case report with genetic analysis

Abstract

BackgroundLeukemoid reaction refers to reactive leukocytosis exceeding 50,000 cells/µl. Chronic neutrophilic leukemia is a rare clonal hematopoietic disorder characterized by sustained mature neutrophilia in the absence of monocytosis or basophilia. The differentiation between leukemoid reaction and chronic neutrophilic leukemia is problematic because both conditions share similar morphological features. Case presentationHere, we present an extremely rare case of a 62-year-old male patient who was initially diagnosed with chronic neutrophilic leukemia at another hospital. When the patient came to our hospital, no mutations in the CSF3R, SETBP1, ASXL1, TET2, SRSF2, SF3B1, ZRSR2 and U2AF1F genes were found by whole-exon sequencing. Further examination revealed the presence of immunoglobulin G kappa myeloma. Meanwhile, colonoscopy showed a mass in the colon, and biopsy confirmed the presence of colon adenocarcinoma. Therefore, we suggest that the increased white blood cell count in the patient was merely a neutrophilic leukemoid reaction caused by synchronous multiple myeloma and colon carcinoma.ConclusionThis is the first report of a case of coexisting multiple myeloma and colon carcinoma presenting with a neutrophilic leukemoid reaction. This case was presented to illustrate that the diagnosis of chronic neutrophilic leukemia must meet the strict WHO diagnostic criteria, especially if there is an underlying plasma cell disorder, and myeloid clonality must be demonstrated to make a distinction between chronic neutrophilic leukemia and leukemoid reaction. Meanwhile, this case provides us with a reference that further examination, especially pathological examination, should be performed on a patient diagnosed with multiple myeloma, who has extramedullary lesions, because other primary tumors may be also presenting the very similar symptoms. Pathological examination is helpful to differentiate the primary tumor from extramedullary invasion of multiple myeloma.