Lethal macrophage-related complications of juvenile myelomonocytic leukemia with a blastic crisis: an autopsy case report

For hematopoietic stem cell transplantation to be successful, complications must be managed. Graft-versus-host disease is particularly important, but various other complications, treatment side effects, and relapse of primary disease may also occur. We report an autopsy case of juvenile myelomonocytic leukemia with a blastic crisis, in which activated and recovered autologous macrophage-related complications after cord blood transplantation caused the patient’s death. Pathological analysis of autopsy specimens revealed diffuse infiltration of mature macrophages into the skin but scarce lymphocytes. These macrophages were found in the bone marrow interspersed with a small number of blasts that had previously occupied about 60% of the bone marrow before death. The direct cause of death was an opportunistic airway infection due to bone marrow and immune failures triggered by overactivation and proliferation of macrophages. Genetic analysis showed the activated macrophages were autologous. Together these findings indicate that the patient died from macrophage-mediated complications, but not from a blastic crisis or conventional graft-versus-host disease. When macrophage activation persists after hematopoietic stem cell transplantation, macrophage-mediated complications should be considered as a differential diagnosis. To manage this complication, pathology specimens should be examined to check for the presence of effector cells at an early stage.