Abstract
Early-onset hemophagocytic lymphohistiocytosis (HLH) can arise as a rare, but important, complication of hematopoietic cell transplantation (HCT) and is difficult to diagnose and treat. It can be considered to be a type of post-transplant cytokine storm syndrome, similar to pre-engraftment immune reaction, engraftment syndrome, other forms of early-onset HLH, and idiopathic pneumonia syndrome. HLH is assumed to be caused by overwhelming activation of monocytes/macrophages. Combined treatment with low-dose etoposide and dexamethasone palmitate has been reported to an effective treatment for early-onset HLH after HCT, as it suppresses abnormally activated monocytes/macrophages. The elucidation of the immunological profile of this condition and the establishment of methods for achieving optimal control of engraftment-related post-transplant cytokine storm syndrome are expected to be achieved in future.
