Suspected Donor-derived Myeloid Neoplasia After Allogeneic HSCT: A Case-based Review of Clonal Evolution.
Giuseppe Mirabile, Roberto Bono, Adele Bottaro et al.
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Case in brief
A 70-year-old woman with acute myeloid leukemia underwent matched unrelated donor allogeneic hematopoietic stem cell transplantation from a 25-year-old female donor. After transplantation, bone marrow examinations showed persistent predominant donor chimerism and progressive expansion of an aberrant myeloid population, from approximately 2% to 14% by multiparametric flow cytometry, without clear morphologic relapse. At hematologic progression, sequencing identified a pathogenic RAS-pathway mutation with a variant allele frequency of 7%, and no molecular features overlapped with the original leukemia. Donor origin remained unconfirmed because pre-transplant sequencing and lineage-specific chimerism data were unavailable.
What made this case unusual
The suspected post-transplant myeloid neoplasm arose despite predominant donor chimerism and without clear morphologic relapse, yet its donor origin could not be definitively established because key pre-transplant and lineage-specific analyses were unavailable.
Diagnostic / clinical pearl
Progressive abnormal myeloid populations after transplantation warrant integrated assessment with serial flow cytometry, molecular profiling, and lineage-specific chimerism; predominant donor chimerism alone does not establish the origin of the abnormal cells.