Clinical Information

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) overlap syndrome characterized by peripheral blood monocytosis (absolute monocyte count ≥1.0 x 10(9)/L, ≥10% of the total white blood cell count) persisting for 3 months or greater. It could be very challenging to distinguish CMML from a reactive monocytosis or from a MPN (such as primary myelofibrosis or polycythemia vera) with monocytosis. Monocytes can be classified into 3 subsets: classical MO1 (CD14+/CD16-), intermediate MO2 (CD14+/CD16+), and non-classical MO3 (CD14-/CD16+) monocytes, with MO1 constituting the major monocyte population (85%) in healthy individuals. Recent reports using multiparametric flow cytometry have demonstrated a characteristic increase in classical monocytes (≥94%) in CMML patients, thus distinguishing them from other causes of reactive and clonal monocytosis with greater than 90% sensitivity and specificity.(1) This panel is designed to analyze the repartition of monocytes in these patients and to give a semiquantitative value for the MO1 compartment. This value will aid in the differential diagnosis and monitoring of CMML.