Hematogones in the peripheral blood of a 5½-month-old boy with cyclic neutropenia due to heterozygous, novel ELANE gene mutation p.Q97P, c.290 A>C.

We have identified a novel point mutation in the ELANE gene of a 5.5-month-old boy with severe cyclic neutropenia, and we are reporting for the first time, to our knowledge, the presence of hematogones in the peripheral blood of an infant. The novel point mutation occurred at base number 290 in codon 97, where adenine was replaced with cytosine. The mutation caused the replacement of amino acid glutamine with amino acid proline in the activation domain of the elastase 2 enzyme. The heterozygous mutation generated severe cyclic neutropenia, granulocytic maturation arrest, an increased number of hematogones (26% of marrow cells) in the bone marrow, an absence of neutrophils, and the presence of stage 3 (mature) hematogones in the peripheral blood. The percentage of hematogones in the peripheral blood was inversely proportional to the absolute number of neutrophils. Leukemic number of blast-like cells (hematogones) in the bone marrow, blast-like cells in the peripheral blood, marked neutropenia, and the arrest of granulopoiesis might suggest an acute leukemia. However, the finding of characteristic flow cytometric features of hematogones should help to avoid a wrong diagnosis.