Myeloid Sarcoma after Allogenic Stem Cell Transplantation forAcute Myeloid Leukemia: Successful Consolidation TreatmentApproaches in Two Patients

Myeloid sarcoma is an extramedullary (EM) manifestation (i.e., manifestation outside the bone marrow) of acute myeloid leukemia(AML); it is assumed to be relatively uncommon and can be the only manifestation of leukemia relapse after allogenic stem celltransplantation (allo-SCT). An EM sarcoma can manifest in any part of the body, although preferentially manifesting in immunologicalsanctuary sites as a single or multiple tumors. ,e development of myeloid sarcoma after allo-SCTis associated with certain cytogeneticabnormalities, developing of graft versus host disease (GVHD), and treatment with donor lymphocytes infusion (DLI). It is believed thatposttransplant myeloid sarcomas develop because the EM sites evade immune surveillance. We present two patients with EM myeloidsarcoma in the breast and epipharynx, respectively, as the only manifestation of leukemia relapse. Both patients were treated witha combination of local and systemic therapy, with successfully longtime disease-free survival. Based on these two case reports, we give anupdated review of the literature and discuss the pathogenesis, diagnosis, and treatment of EM sarcoma as the only manifestation of AMLrelapse after allo-SCT. ,ere are no standard guidelines for the treatment of myeloid sarcomas in allotransplant recipients. In ouropinion, the treatment of these patients needs to be individualized and should include local treatment (i.e., radiotherapy) combined withsystemic therapy (i.e., chemotherapy, immunotherapy, DLI, or retransplantation). ,e treatment has to consider both the need forsufficient antileukemic efficiency versus the risk of severe complications due to cumulative toxicity.