A case of neonatal alloimmune neutropenia with an uncommon presentation

Neonatal alloimmune neutropenia (NAN) is a rare condition in neonates, with an incidence of < 0.1%. It occurs when maternal antibodies against neutrophil antigens inherited from the father cross the placenta, destroying the neutrophils of the fetus and/or the newborn. We report a case of a female neonate who started exhibiting scattered petechiae over the trunk and lower limbs, a day after birth. The blood count revealed severe neutropenia and mild thrombocytopenia. Infections were excluded. Flow cytometry analysis confirmed the presence of antineutrophil immunoglobulin G antibodies in the newborn's neutrophil membrane and in the mother's serum. When screened for polymorphisms in the genes encoding for human neutrophil antigens (HNA), we identified HNA-1b and/or HNA-3a as potential causes of the mother/daughter incompatibility. Even though neutropenia is usually self-limiting, neonates with NAN are at risk of developing severe infections. Therefore, early identification of these patients can prevent serious complications.