Acute Lymphoblastic Leukemia

In acute lymphoblastic leukemia (ALL), too many immature lymphocytes are present in the bone marrow and the blood. Normally, these cells are relatively rare, but in ALL, they continuously multiply and are overproduced by the bone marrow, causing fatigue, anemia, fever, and bone pain due to the spread of these cells into the bone and joint surfaces. This slide shows many more immature lymphocytes than you would typically expect to see in a blood smear.