Reference guide for adult chronic neutropenia

: Chronic neutropenia is a rare hematological entity characterized by isolated neutropenia without anemia or thrombocytopenia. The diagnostic criteria and classification of chronic neutropenia have been more elusive in adult cases than pediatric cases. We herein propose the Reference Guide for Adult Chronic Neutropenia. In this guide, diagnosis of chronic neutropenia is based on recurrent or continuous neutropenia defined by absolute neutrophil count (ANC) less than 1,500/µl for over three or more months. Severity of chronic neutropenia is defined as follows: severe, ANC <500/µl; moderate, ANC between 500 and 1,000/µl; mild, ANC between 1,000 and 1,500/µl. In this guide, adult chronic neutropenia is classified into several types including autoimmune neutropenia, cyclic neutropenia, chronic neutropenia with T cell clone, and chronic idiopathic neutropenia with or without family history, and their clinical characteristics are described. Together with antibiotics, granulocyte colony-stimulating factors (G-CSFs) constitute the first-line treatment for adult chronic neutropenia patients at time of bacterial infections. Prophylactic use of G-CSFs or antibiotics is recommended only in selected clinical settings in severe cases.