Features of CNL:
(1) prolonged neutrophilia consisting predominantly of band forms and segmented neutrophils
(2) no significant increase in myeloblasts, promyelocytes, myelocytes, metamyelocytes, eosinophils or basophils
(3) myeloid hyperplasia of the bone marrow
(4) hepatosplenomegaly
(5) absence of the Philadelphia chromosome and BCR/abl gene mutations
(6) exclusion of other kinds of chronic myeloproliferative disorder
(7) exclusion of reactive causes of a neutrophilic response or leukemoid reaction
Laboratory findings:
(1) elevated vitamin B12
(2) elevated leukocyte alkaline phosphatase
(3) low serum granulocyte colony stimulating factor (G-CSF)
(4) abnormal neutrophil clonality in specialized molecular testing
