[Successful treatment with pseudo-autologous blood stem cell transplantation for an adolescent-onset multiple myeloma who relapsed after allogenic bone marrow transplantation].

A 14-year-old male with multiple myeloma (IgG-λ, ISS stage 3) received myeloablative matched unrelated bone marrow transplantation, and achieved a complete response. At 16 months after the transplantation, he relapsed. The relapse was resistant to bortezomib and thalidomide. Peripheral blood showed mixed chimerism with 10% recipient cells. Peripheral blood stem cells (PBSC) were collected and pseudo-autologous PBSC transplantation (PASCT) was performed following high-dose melphalan without graft-versus-host disease prophylaxis. Hematopoietic recovery was prompt and a partial response was obtained without graft-versus-host disease exacerbation. We have presented a rare case of adolescent-onset multiple myeloma, obtaining a transient response with PASCT following post-allogeneic transplant relapse.