Acute Lymphoblastic Leukemia in dogs and cats
Leukemia is a malignant neoplasm that originates from hematopoietic precursor cells in the bone marrow. There are aleukemic leukemias in which there is a proliferation of cells in the bone marrow but the cells do not appear in the circulation. Normally leukemia is the presence of abnormal white blood cells in the blood. Lymphocytes are the white blood cells formed in lymphatic tissue (such as the lymph nodes, spleen, tonsils) throughout the body. Sometimes lymphocytes are formed in the bone marrow. Acute lymphoblastic leukemia is the form of leukemia in which the white blood cells circulating in the blood are chiefly lymphoblasts (young immature cells that mature into lymphocytes). Lymphoblasts should not be in the circulating blood because they normally mature in lymphatic tissue. Therefore, lymphoblasts in the circulating blood are abnormal. Acute lymphoblastic leukemia is characterized by penetration or infiltration of excessive numbers of lymphoblasts into the bone marrow, and sometimes other organs. These infiltrates cause damage to the organs.
Acute lymphoblastic leukemia in a dog. Numerous lymphoblasts were found in this blood smear.
-Acute lymphoblastic leukemia is defined as the presence of circulating neoplastic prolymphocytes and lymphoblasts in the blood.-Animals with acute lymphoblastic leukemia have impaired humoral and cellular immunity.-Acute lymphoblastic leukemia is characterized by bone marrow infiltration (and extramedullary sites) and displacement of normal hematopoietic stem cells.-Other organs can be infiltrated.