Demonstration of clonality in neutrophils using FISH in a case of chronic neutrophilic leukemia.

A patient previously diagnosed with chronic neutrophilic leukemia (CNL) was studied using fluorescent in situ hybridization (FISH) to determine clonality of neutrophils. By cytogenetic studies the patient's blood and bone marrow had an 11q14 deletion and were negative for the Philadelphia (Ph) chromosome. FISH was performed on peripheral blood smears using probes for the bcr/abl translocation and a probe for 11q23 (MLL). The patient's white blood cells were negative for the bcr/abl translocation; neutrophils and eosinophils, but not lymphocytes, were monosomic for the 11q23 probe indicating a clonal population within the neutrophil population.