Donor cell leukemia following unrelated donor bone marrow transplantation for primary granulocytic sarcoma of the small intestine

Granulocytic sarcoma (GS) in the absence of bone marrow involvement at diagnosis is unusual. Treatment of primary (aleukemic) GS should follow intensive acute myeloid leukemia (AML)-style chemotherapy protocols, as patients otherwise appear destined to rapidly declare frank medullary disease. However, the role of hematopoietic stem cell transplantation (HSCT) is less clear. Here we present an unusual case of isolated primary GS involving small bowel treated with chemotherapy consolidated by HSCT from an unrelated donor. Full donor chimerism was achieved and maintained, without relapse of the original disease. However, 28 months post-transplant our patient developed a distinct and rapidly progressive medullary AML, apparently derived from transplanted cells of donor origin. Donor cell leukemia (DCL) is a fascinating and increasingly recognized phenomenon, with at least 50 cases reported to date. Our case adds to this growing literature and highlights the ethical dilemmas concerning notification of unrelated donors in such cases, since there is little evidence that they are at increased risk of developing leukemia themselves. This also represents the first case of DCL reported after transplantation for primary GS.