Two Cases of Donor-Derived Malignancies Following Allogeneic Hematopoietic Stem Cell Transplantation

Herein, we present the clinical and laboratory characteristics of two patients who developed donor-derived malignancies following allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute myeloid leukemia (AML). The first case developed 5q- myelodysplastic syndrome (MDS) approximately 6 months following allo-HSCT. The etiology was inadvertent transfer of cancer cells from the donor to the recipient; we were able to confirm this by performing fluorescent in-situ hybridization (FISH) on a portion of the original pheresis product. The stem cell donor was subsequently diagnosed with 5q- MDS. The second case developed donor-derived AML 23 years post allo-HSCT, the longest reported interval from allo-HSCT to donor-derived malignancy. The etiology of case 2 is unclear but could have occurred due to the presence of oncogenes in the donor cells at transplantation or new somatic mutations that occurred posttransplantation. The stem cell donor has not developed MDS or AML.