The proportion of immature myeloid cells (promyelocytes, myelocytes, and metamyelocytes) in PB, as well as the presence of dysplasia, are key criteria for the differential diagnosis against a rare BCR::ABL1-negative myeloproliferative neoplasm named chronic neutrophilic leukemia (CNL), as in CNL, the dysplasia is absent, the percentage of immature elements is always <10%, and persistent peripheral blood neutrophilia (WBC > 25 × 109/L, with >80% segmented neutrophils plus banded neutrophils) is present [2,40]. The gene discussed is BCR; the disease is chronic neutrophilic leukemia.