A Case of Omphalitis Revealing Alloimmune Neonatal Neutropenia

Neutropenia, characterized by a decrease in peripheral blood neutrophil count less than 1500/µL, poses significant clinical challenges due to its association with recurrent infections. This paper presents a rare and intriguing case of alloimmune neonatal neutropenia (ANN), an uncommon variant of neutropenia instigated by the transplacental transfer of maternal anti-neutrophil antibodies that consequently induce opsonization and phagocytosis of the neonate's neutrophils within the reticuloendothelial system. The patient, an 18-day-old boy, was born at 36 weeks five days of gestation and weighed 2465 g, an attribute considered appropriate for gestational age (AGA). He experienced multiple episodes of skin and respiratory infections, coupled with delayed umbilical cord separation and demonstrated a significant reduction in neutrophil count. Despite these symptoms, the patient did not develop bacteremia and his condition improved with antibiotic therapy, leading to his discharge from the hospital. Crucially, both the patient and his mother tested positive for anti-HNA (human neutrophil alloantigen)-1a and anti-HNA-1b antibodies, indicative of a diagnosis of ANN. ANN is intriguing in its clinical course, where despite neutropenia, severe infections are relatively uncommon, and the majority of cases resolve spontaneously within several months post-birth as the maternal antibodies diminish. Nevertheless, there have been reports of moderate to severe infections, demanding clinical intervention and close patient monitoring. The patient in our case was treated with prophylactic antibiotics for six weeks, until a rise in neutrophil count was confirmed, stemming from the severity and recurrence of infections. The issue of using antibiotics and granulocyte colony-stimulating factor (G-CSF) agents in the treatment of ANN remains contentious, with contrasting reports regarding their efficacy and safety. The balance between the prospective therapeutic advantages, potential risks such as antibiotic resistance, and the possibility of inducing leukemia with long-term administration of G-CSF agents necessitates meticulous deliberation. This case underscores the crucial role of early recognition of ANN in neonates presenting with neutropenia. Prompt diagnosis enables a more targeted approach to treatment, reduction in unnecessary antibiotic administration, and specific testing, thus impacting the overall patient management and potentially improving outcomes. Furthermore, in the event of delayed umbilical cord separation in neonates, healthcare providers should consider ANN and other immunodeficiencies related to neutrophil functional abnormalities as potential diagnoses. This patient's story accentuates the need for further investigations to elucidate the precise etiology and pathogenesis of ANN, paving the way for improved diagnostic tools and effective therapeutic strategies.