Rescue by hematopoietic progenitor cells derived from engrafted cord blood unit in a child with brain tumor after transplantation for T-cell acute lymphoblastic leukemia.

An 8-year-old boy with T-cell acute lymphoblastic leukemia received unrelated cord blood transplantation in April 2006. His course was uneventful until February 2007, when a hyperintense lesion was noted in the pons. A subsequent bone marrow examination confirmed that he was in remission with full donor chimerism. He was therefore diagnosed with an inoperable brain tumor after cord blood transplantation. Despite radiotherapy for the brain lesion, his neurological status worsened. High-dose chemotherapy with "autologous" progenitor cell rescue was adopted, although the fact that these cells were originally derived from engrafted umbilical cord unit. He was in apparent remission of his brain tumor for 3 years.