Engraftment syndrome (ES) is a febrile syndrome that occurs after hematopoietic stem cell transplantation during the early phase of neutrophil recovery. Clinical features, which are variably present, include rash, pulmonary edema, diarrhea, hepatic dysfunction, renal dysfunction, and altered mental status. For a diagnosis of ES to be met, the onset of symptoms must be within 1-4 days of neutrophil recovery, which occurs 7-14 days after transplantation.

The pathophysiology of ES is not clear, but is thought to involve an excess of pro-inflammatory cytokines, such as tumor necrosis factor and interleukin-1, which in turn may activate cytotoxic T-cells.

ES is typically seen after autologous transplantation, though has been reported after allogeneic transplantation as well. Potential risk factors for ES include exposure to granulocyte colony-stimulating factor (G-CSF), certain conditioning regimens (such as cyclophosphamide), and select chemotherapeutic agents, such as proteasome inhibitors. Large, multicenter trials are needed to confirm and identify additional risk factors for ES.

There are similar occurrence rates of ES between children and adults, and they also share a similar presentation. However, there is a higher nonrelapse mortality rate in children with ES.