In addition, leukemias are classified as either acute, referring to a rapidly progressing disease that involves immature leukocytes, or chronic, referring to a slower proliferation involving mature white cells. In acute leukemias, immature nonfunctioning leukocytes called blast cells proliferate. The lymphocytic leukemias affect the white blood cells that give rise to various types of lymphocytes. Each of these types may be further classified into subtypes. Symptoms Many of the symptoms of acute leukemia can be attributed to anemia , which results from the attrition of red blood cells as they are crowded out by the leukemic cells.
Frequent infections result from a dearth of functioning white blood cells.
Bone tenderness may also be present. Hemorrhaging may develop because blood-clotting elements are scarce. Blasts may congregate in the lymph nodes, spleen, and liver, causing enlargement and pain, or they may invade the central nervous system, causing dizziness, headache, or fever. If untreated, death can supervene rapidly in acute leukemia. Patients with chronic leukemias often have no symptoms and may be hard to diagnose, but less virulent versions of the symptoms seen in the acute leukemias may be present.