The various forms of leukemia are fatal diseases characterized by uncontrolled proliferation of leukopoietic tissue. The cell may be myelocytic, lymphocytic or monocytic. The diseases may be acute, subacute, or chronic. In the acute form, myeloblasts, lymphoblasts or monoblastic cells are seen in the peripheral circulation or are found in increased numbers in the bone marrow. In the chronic varieties immature cells more highly differentiated than the blast stage are found either in the circulation or in predominant numbers in the bone marrow. Anemia is present and is more severe in the acute or terminal phases, it is associated with thrombocytopenia and a tendency to hemorrhage. Not all leukemias have a high white count, even though the leukopoietic tissues are hyperplastic, because the marrow may be unable to mobilize the cells. In such cases the white count will be low or normal with the presence of a few immature leukocytes. Such leukemias are called aleukemic, leukopenic or subleukemic.In nearly all forms of leukemia the liver, spleen and lymph nodes are infiltrated, in addition to the bone marrow. The liver is often conspicuously enlarged. In myelogenous leukemia, the spleen may weigh as much as 5,000 Grams. and a diagnosis of this form of leukemia is favored clinically when increased numbers of atypical leukocytes are found in the circulating blood in the presence of pronounced splenomegaly. In lymphocytic and monocytic leukemia, the lymph nodes are usually enlarged. Inflamed or bleeding gums are often important clinical manifestations. Secondary infiltrations may be found in any organ in all varieties of leukemia. Involvement of the skin is known as leukemia cutis. Massive growths may occur in the osseous or periosseous structures. Terminal infections or hemorrhages are usually associated with the profound anemia or thrombocytopenia that results from leukemic replacement of the normal marrow.
