Algorithm for workup of neutrophilic leukocytosis. Red highlights indicate findings that exclude a diagnosis of CNL, yellow highlights indicate findings that are relative contraindications to CNL, and green highlights indicate findings that support a diagnosis of CNL. *Evaluation for signs of infection, underlying neoplasm (including plasma cell neoplasm), drug reaction, or inflammatory condition. **Should include RT-PCR and/or FISH testing that will detect all BCR::ABL1 isoforms ⁺NGS can be performed on blood or bone marrow specimen. ^{^}RNA-seq or NGS-based RNA fusion assay to detect fusions of PDGFRA, PDGFRB, FGFR1, FLT3, JAK2, or ABL1 with various partners; FISH testing for these fusions can also be performed but may miss some fusions.