Isolated Chronic Neutropenia in Adults: Causes, Diagnostic Work-Up, and Management—A Narrative Review

Neutropenia is certainly of clinical significance due to its increased risk of infections in most patients. Chronic neutropenia is defined as neutropenia that persists for more than 3 months. Isolated chronic neutropenia is rare in clinical practice, and its differential diagnosis can be challenging. This rare entity is the focus of this review. Here, we examine the common causes (drugs, hereditary, autoimmune, and idiopathic), diagnostic work-up, and management of chronic isolated neutropenia in adults. We also discuss the Duffy-null-associated neutrophil count (DANC), which has a high prevalence (80-100%) in Sub-Saharan Africans and in Arabs and is not considered a medical condition. It should be highlighted that management decisions in patients with chronic isolated neutropenia should be individualized, mainly taking into account their clinical history over the neutrophil count alone. In this narrative review, we exclusively focus on non-malignant, non-cytotoxic and non-chemotherapy-induced forms of isolated chronic neutropenia in adults.