[Erythrocytosis following allogeneic hematopoietic stem cell transplantation]

Post-transplant erythrocytosis (PTE) following allogeneic hematopoietic stem cell transplantation (alloHSCT) is rare, and the clinical characteristics of this condition remain unknown. In this study, we examined the clinical characteristics of three PTE cases among 321 patients who received allo HSCT from January 1992 to December 2011 at our institution. All three patients exhibited normal levels of white blood cell and platelet counts when their hemoglobin levels reached their peak. Two patients exhibited normal levels of erythropoietin. No thrombosis or hemorrhage was observed in any of the three patients without cytoreductive therapy or an antiplatelet agent. All three patients tested negative for JAK2V617F mutations. Two patients had high levels of IL-13, an upstream signal for the JAK/STAT pathway. JAK2 is known to significantly contribute to the pathology of polycythemia vera; however, this pathology may differ from that of PTE. We believe that it is necessary to construct a more appropriate management structure for PTE by analyzing more case data in the future.