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235 Donor Derived Myelodysplastic Syndrome in a Pediatric Allogeneic Transplant Recipient Amos Gaikwad2,3,4,5, Challice L. Bonifant2,3,4, Pulivarthi H Rao2,3,4, Dolores Lopez-Terrada1,4, Michael Cubbage2,3,5, Robert Krance2,4, and Andrea M. Sheehan1,2,4 Departments of Pathology1, Pediatric-Hematology-Oncology2, Texas Children’s Cancer & Hematology Centers3, Baylor College of Medicine4 and Texas Children’s Hospital5 Background: Emergence of leukemic transformation post-bone marrow transplantation (BMT) is reflective of disease recurrence in the vast majority of cases. However, de novo development of myelodysplastic syndrome (MDS) or frank leukemia can also occur in donor derived hematopoietic cells. Though rare, recognition of this entity is critically important given the implications for treatment design and disease monitoring. The phenomenon can also provide a unique platform to study leukemogenesis and the role of bone marrow environment. Utilization of current cytogenetic and flow cytometry techniques can easily and accurately identify dysplastic cell origin and this information should be included in routine disease monitoring post-transplantation. Objective: Presentation of a single case to highlight the diagnosis of donor-derived leukemia based on combined cytogenetic and flow cytometric techniques. Case presentation and results: A 17 year old male patient presented with pancytopenia and was subsequently found to contain 26% blasts in his bone marrow (BM) expressing CD117 and CD13 consistent with acute myeloid leukemia (AML). Cytogenetic analysis showed 32% of the BM cells contained a 13q14.3 deletion. He was treated on the Children’s Oncology Group (COG) protocol AAML0531 (standard arm) and achieved remission after two cyles of chemotherapy. Following completion of his next cycle, he proceeded to a mismatched related donor allogeneic stem cell transplant. His mother was a 5/6 HLA match. He received two CD34+ enriched donor lymphocyte infusions in the post-transplant period to strengthen engraftment. Four years post-transplant, the patient showed 15% blasts in BM expressing CD34 in addition to CD117 and CD13, similar to the initial clone. Cytogenetic analysis demonstrated 99.8% donor cells (XX) with monosomy 7 in 78% of the cells and no evidence of 13q14.3 deletion, indicating a new clone derived from the donor cells. Conclusions: Donor derived leukemia is a rare, but clinically important entity. When considering the presented case, flow cytometry was critical in initially detecting the abnormal blast population as well as the malignant cells post BMT that directed the cytogenetic analysis to examine the donor cells. Therefore, the synergistic review of cytogenetic, and flow cytometric data is necessary to accurately follow disease at diagnosis and at relapse. |
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