Conclusions

Neutrophilia in MM has two main differential diagnoses: leukemoid reaction and hematologic neoplasms, such as CNL. Both leukemoid reaction and CNL manifest toxic granulation and Döhle bodies. Both can present with constitutional symptoms, such as fevers, chills, fatigue, and weight loss; however, patients could be asymptomatic in either case. Thus, it is important to distinguish the two in order to guide treatment and prognostication. Leukemoid reaction secondary to infections would not have blasts on peripheral smear and may yield positive cultures. The diagnosis of CNL, however, is based on set criteria; the WHO definition from 2022 is the most sought-after. The use of chemotherapy, especially alkylating agents and lenalidomide, increases the risk of developing hematologic malignancies following ASCT in MM.