Chronic neutrophilic leukemia. A study of four cases

Chronic neutrophilic leukemia (CNL) is a very rare entity, which has to be included among the chronic myeloid leukemias. Once an underlying cause of neutrophilia is excluded, the diagnosis of CNL is based on exclusion of chronic granulocytic and other types of chronic myeloid leukemias. The classification proposed by Sheperd et al. has proven to be helpful, but it must be completed by cytogenetic analysis and the search for bcr rearrangement by molecular biology methods, in order to confirm the absence of Philadelphia chromosome and of bcr-abl hybrid gene. We report here four cases of CNL, with confirmed absence of bcr rearrangement in two cases. Two patients died, 12 and 8 years after diagnosis, the second one following transformation into myelofibrosis with myeloid metaplasia. The other two died of acute myelogenous leukemia, the first one, 25 years after diagnosis of CNL, following a 3-year phase of acceleration. The last patient presented combined features of CNL and refractory anemia with excess of blasts, and was characterized by both progressive leukocytosis and severe thrombocytopenia; acute transformation into acute myelogenous leukemia occurred 6 months after diagnosis and death 1 month later. Among the 30 cases reported so far, plus the four presented here, combined myelodysplastic features were observed in five cases and transformation into acute myelogenous leukemia in six. Chronic neutrophilic leukemias should be reported regularity, in view of the uncertain and low frequency of this hematological disease.