Neutrophilic hyperleukocytosis in the multiple myeloma onset

Abstract

Neutrophilic leukocytosis is not specific for multiple myeloma (MM) and is a reason for the exclusion of myeloproliferative neoplasm.A clinical case of MM patient with neutrophilic hyperleukocytosis (75 х 109/L), liver and spleen enlargement at the disease onset is presented. Examination did not reveal t(9;22), BCR/ABL gene and JAK2V617F mutation. To exclude the combination of MM with chronic neutrophilic leukemia, a study of the clinically significant part of the CSFR3R gene was performed. The absence of a CSFR3R gene mutation made it possible to exclude chronic neutrophilic leukemia and start MM treatment. After the 1st therapy course with bortezomib, cyclophosphamide and dexamethasone, blood counts returned to normal, liver and spleen size decreased. After 6 therapy courses, complete hematological remission was achieved. An attempt to mobilize peripheral blood stem cells with cyclophosphamide was unsuccessful. The effectiveness of antimyeloma therapy proved the correctness of the diagnosis and the chosen treatment tactics.Neutrophilic leukocytosis in MM is explained by the ability of plasma cells to synthesize granulocyte colony-stimulating factor in some cases. In the presence of a plasma cell tumor, the analysis of the CSFR3R gene may be of decisive importance in the differential diagnosis of reactive neutrophilic leukocytosis due to MM and the combination of MM with chronic neutrophilic leukemia.