An unusual extramedullary relapse of acute nonlymphocytic leukemia after allogeneic bone marrow transplantation

Recurrent leukemia following allogeneic bone marrow transplantation (BMT) for acute nonlymphocytic leukemia (ANLL) continues to be a cause of morbidity and mortality. Most relapses occur within the first 6-12 months, although disease-free survival curves do not begin to plateau until 24 months posttransplant. The majority of relapses occur in the bone marrow. Extramedullary relapses usually occur in "sequestered sites," i.e., the testis and central nervous system. Although the true incidence of extramedullary relapse in "nonsequestered" sites after allogeneic BMT for ANLL is unknown, it appears that this type of relapse is distinctly unusual. The authors present a case of an unusual extramedullary relapse of ANLL in the breast at day +613 after allogeneic BMT for ANLL. In addition, we briefly review the English BMT literature and discuss the differential diagnosis of breast masses in women who survive allogeneic BMT for ANLL.