Objectives: Multiple myeloma (MM), a neoplastic proliferation of plasma cells, is a common diagnosis among hematologic malignancies. Leukocytosis, specifically neutrophilia, is also very common, typically as a secondary abnormality. However, having both multiple myeloma and neutrophilia simultaneously is rare and could arise by two distinct pathways: either by separate, but concurrent, clonal neoplasm of neutrophils (e.g chronic neutrophilic leukemia) or by a paraneoplastic-type process thought to be secondary to plasma cell stimulation of granulocyte colony-stimulating factor (G-CSF). Distinguishing between the two determines treatment and prognosis.
Methods: A retrospective evaluation of two cases of MM with neutrophilia and comprehensive literature search for all MM with neutrophilia reported in the literature was completed.
Results: We report two cases in which persistent neutrophilia was related to underlying multiple myeloma. One case showed trending of neutrophilia concordant to the varying response of his MM to multiple pharmacotherapies, and the other case had steadily elevated neutrophils without worsening symptoms in the setting of observation alone.
Conclusions: After thorough evaluation of the literature and detailed comparison with our two new cases, a flow chart is presented to differentiate neutrophilia secondary to MM from other differential diagnoses, which could affect treatment options and potentially have prognostic implication.
Multiple myeloma, Neutrophilia, Leukocytosis, Gammopathy, Chronic neutrophilic leukemia