leukemia /lo̅o̅kē″mē·ə/ [Gk, leukos + haima, blood] , a group of malignant neoplasms of hematopoietic tissues characterized by diffuse replacement of bone marrow or lymph nodes with proliferative white blood cell precursors. Peripheral blood WBC counts become elevated, and immature or variant forms appear in the peripheral blood. Leukemia may be chronic or acute, lymphoid, myeloid, or erythroid. In some chronic leukemias, when untreated, the WBC count becomes grossly elevated and the blood may appear whitish, giving leukemia its name. Also spelled leukaemia. See also acute childhood leukemia, acute lymphocytic leukemia, acute myeloid leukemia.
