How I treat hematologic emergencies in adults with acute leukemia.

Acute myeloid leukemia and acute lymphoblastic leukemia remain devastating diseases. Only approximately 40% of younger and 10% of older adults are long-term survivors. Although curing the leukemia is always the most formidable challenge, complications from the disease itself and its treatment are associated with significant morbidity and mortality. Such complications, discussed herein, include tumor lysis, hyperleukocytosis, cytarabine-induced cellebellar toxicity, acute promyelocytic leukemia differentiation syndrome, thrombohemorrhagic syndrome in acute promyelocytic leukemia, L-asparaginase-associated thrombosis, leukemic meningitis, neutropenic fever, neutropenic enterocolitis, and transfussion-associated GVHD. Whereas clinical trials form the backbone for the management of acute leukemia, emergent clinical situations, predictable or not, are common and do not readily lend themselves to clinical trial evaluation. Furthermore, practice guidelines are often lacking. Not only are prospective trials impractical because of the emergent nature of the issue at hand, but clinicians are often reluctant to randomize such patients. Extensive practical experience is crucial and, even if there is no consensus, management of such emergencies should be guided by an understanding of the underlying pathophysiologic mechanisms.