Extramedullary involvement is considered to be an uncommon presentation of acute myeloid leukemia (AML), although some data suggest it may be present in up to 30% of patients. Extra-medullary involvement by AML can present in a variety of clinical manifestations, most notably in the form of myeloid sarcoma, leukemia cutis, and central nervous system involvement. Each presents a unique clinical scenario in terms of symptoms and management. Extramedullary disease in any form presenting without evidence of bone marrow disease is still considered evidence of systemic disease and is usually treated as such. Most commonly, extramedullary disease presents concurrently with bone marrow disease, and although it may require additional local therapy in the form of intrathecal chemotherapy or radiation, the principles of systemic treatment remain unchanged. The prognostic impact of extramedullary disease is unclear. Specifically, whether hematopoietic stem cell transplantation should be considered in first remission irrespective of other prognostic factors has not been established. Patients who undergo transplantation have similar outcomes as patients without extramedullary disease, although they do have a higher rate of extramedullary relapse. More research is needed to define the molecular basis for extramedullary disease, its prognostic impact, and optimal management.
Bone Marrow Transplantation Central Nervous System