Hyperacute graft-vs.-host disease after related HLA-identical umbilical cord blood transplantation

haGVHD has been described following bone marrow and peripheral blood stem cell transplantation and in a single case who received unrelated HLA mismatched CB. An unusual case of haGVHD following HLA 6/6-matched sibling CBT in a child with AML is presented. The development of haGVHD in a fully matched CBT and without precipitating factors may suggest the role of still undefined and perhaps individual contributory factors.