In 1956 Kostmann described a condition of neutropenia and repeated bacterial infections in infancy that he termed infantile genetic agranulocytosis. Subsequently, 120 patients with Kostmann syndrome have been reported, but no cases have been reported in neonates delivered prior to 33 weeks of gestation. Since the incidence of preterm delivery is about seven percent, it would have been anticipated that 8 to 12 of the 120 reported cases would have been delivered prematurely or received NICU care. We speculate that in preterm infants who die with bacterial sepsis, the diagnosis of Kostmann syndrome can be missed, because their neutropenia can be ascribed solely to bacterial sepsis, and the underlying cause of their neutropenia is never suspected or detected. We report prematurely delivered twins, in whom the“A” twin died with bacterial sepsis and neutropenia, and Kostmann syndrome was not considered. The “B” twin was also found to be neutropenic, and his bone marrow findings and clinical course were consistent with Kostmann syndrome. We observed two other preterm infants in whom the diagnosis of Kostmann syndrome was made in NICUs within the State of Florida. These four patients were all preterm (26,28,28, and 32 wks gestation), all presented with profound neutropenia during the first weeks of life, had marrow aspirates with an “arrest” at the promyelocyte or myelocyte stage, and had negative studies for isoimmune, cyclic and other varieties of neutropenia. All responded to recombinant granulocyte colony-stimulating factor (rG-CSF), and all remitted while off rG-CSF. Neutropenia is very common in preterm infants, and certainly very few of these will have Kostmann syndrome as the etiology. Nevertheless, when neutropenia is observed in a preterm infant, and other causes for the neutropenia have been excluded, the diagnosis of Kostmann syndrome should be considered so that appropriate therapy and followup can be instituted.
