Extramedullary relapse of acute lymphoblastic leukemia in breast: a rare presentation.

Unusual sites of relapses following allogenic hematopoietic stem cell transplantation (HSCT) for acute lymphoblastic leukemia (ALL) are rarely reported. Our report describes a thirty-two-year old female, who developed extramedullary (EM) breast relapse after allogenic HSCT for pre B cell Philadelphia chromosome negative ALL. She had no evidence of leukemia in her marrow demonstrating 100% full donor chimerism, while she had ALL relapse in her breast.