Extramedullary sites of leukemia relapse after transplant.

Recurrent or residual leukemia found in extramedullary sites after intensive treatments adversely affects prognosis. To summarize the sites and outcomes when extramedullary relapses have been reported after stem cell transplants, and to elucidate when long survival has been achieved, 207 cases were analysed. Authors were contacted for follow-up information. The most commonly reported sites are soft tissue in acute leukemias and bone in CML. Extramedullary relapse occurred typically within 2 years in ALL, but later in one-third of myeloid leukemias. Most testicular relapses reported in AML followed non-TBI conditioning. Marrow relapse was not inevitable if aggressive treatment was begun early. Local therapy alone was generally inadequate. Intensive therapy has produced lengthy remissions in cases of acute leukemias involving various sites, whereas CML cases, particularly involving bone, were most resistant to treatment. Heightened awareness and aggressive treatment should improve the prospect for cure after extramedullary relapse.