Donor cell-derived chronic myelomonocytic leukemia presenting after allogeneic hematopoietic cell transplantation for T-cell acute lymphoblastic leukemia.

Donor cell leukemia is a very rare cause of relapse after allogeneic hematopoietic cell transplantation (alloHCT). Herein, we describe an unprecedented case of donor cell-derived chronic myelomonocytic leukemia (CMML) presenting seven years after a 51-year-old man received a matched-related alloHCT from his 59-year-old brother for T-cell acute lymphoblastic leukemia.