Conditions Treated by the Leukemia and Lymphoma Program Acute lymphoblastic leukemia (ALL), also called lymphocytic or lymphoid leukemia, is the most common form of leukemia in children. In this form of leukemia, the bone marrow makes too many lymphocytes (a type of white blood cell that help fight infection). These lymphocyte cancer cells, also called blasts, are not normal and do not fight infection well. Acute myeloid leukemia (AML), also called myelogenous, granulocytic, myelocytic or myeloblastic leukemia, is the second most common blood cancer in children. AML affects certain cells in the bone marrow (myeloid cells). These cells ordinarily develop into normal, mature blood cells, but with AML, these immature cells do not develop properly and become cancerous. Chronic myeloid leukemia (CML), also called chronic myelogenous leukemia, is a type of cancer affecting the blood and bone marrow. In CML, the bone marrow—the soft, spongy center of the bone where blood cells form—produces too many white blood cells. White blood cells normally help fight infection and disease. But in CML, the white blood cells become abnormal. They begin to grow too fast and crowd out normal, healthy cells. Hodgkin lymphoma is a cancer that starts in a white blood cell called a B lymphocyte. Healthy B lymphocytes are part of the immune system. In Hodgkin lymphoma, some of the B lymphocytes are no longer healthy and do not fight infection. Instead, the abnormal (cancerous) lymphocytes begin to grow out of control, causing the lymph nodes to get bigger. Non-Hodgkin lymphoma (NHL), including both B- and T-cell subtypes, starts in a cell called a lymphocyte. With NHL, abnormal (cancerous) lymphocytes divide rapidly, crowding out the normal cells. NHL may spread to the bone marrow, central nervous system, liver, spleen and reproductive organs. B-cell lymphoma is a form of cancer that starts in a white B cell called a lymphocyte. Mixed phenotype acute leukemia (MPAL) is a very rare type of leukemia where more than one type of leukemia occurs at the same time. Post-transplant lymphoma and lymphoproliferative disorders (PTLD) are a group of potentially life-threatening conditions that affect patients who have had an organ or bone marrow transplant. PTLD occurs because the immune system of these patients is weakened with medication to allow them to accept the newly transplanted organ or bone marrow. Myelodysplasic disorders (MDS) are bone marrow disorders that can lead to acute myeloid leukemia. MDS occurs when young blood cells in the bone marrow do not develop properly into healthy white cells, red blood cells or platelets. This leads to a shortage of healthy white cells (which fight infection), red blood cells (which carry oxygen), or platelets (which help your blood clot). Leukemia and lymphoma that occur in people who have an increased risk of developing these cancers, including people with Down syndrome and Fanconi anemia.