Experimental design of treatment of children, adolescent and young adults with recurrent/refractory mature B-NHL. allo, allogeneic; auto, autologous; MMF, mycophenolate mofetil; MRD, matched related donor; MUD, matched unrelated donor; NHL, non-Hodgkin lymphoma; PBSC, peripheral blood stem cell; SCT, stem cell transplantation; UCB, umbilical cord blood.