Isolated breast relapse after allogeneic bone marrow transplantation for childhood acute lymphoblastic leukemia.

Unusual sites of relapses following bone marrow transplantation (BMT) for childhood acute lymphoblastic leukemia (ALL) are rarely reported. We report the case of a 16-year-old girl who presented with an isolated right breast relapse 8 months after allogeneic BMT for ALL in second remission. Biopsy showed an ALL infiltrate. Bone marrow and CSF were normal. The girl never showed before extramedullary involvement. She was treated with local radiotherapy and mild systemic chemotherapy. Nine months after breast relapse, she presented an isolated central nervous system relapse. The treatment of isolated extramedullary relapses following BMT is still controversial.