[Successful outcome of allogeneic hematopoietic stem cell transplantation for systemic mastocytosis complicated with acute myeloid leukemia].

A 60-year-old woman developed a fifth thoracic spine fracture with progressive paraplegia and underwent posterior spine fusion in June 2018. Based on the histopathological analysis of the surgical specimen, she was diagnosed with KIT D816V-positive systemic mastocytosis (SM). In June 2019, peripheral blood examination revealed remarkable eosinophilia. She was given prednisolone, which resulted in the resolution of eosinophilia. In May 2020, she developed acute myeloid leukemia (AML). Induction therapy was initiated and complete remission achieved. Subsequently, she received one course of consolidation therapy and allogeneic hematopoietic stem cell transplantation (allo-SCT). Although the residual mast cell tumor aggravated during chemotherapy for AML, the tumor regressed after allo-SCT, suggesting a graft-versus-mastocytosis effect. Nine months after the transplantation, the patient is alive and healthy without recurrence of AML and SM.