Pseudoleukemia

PSEUDOLEUKEMIA (pseudoleukaemia), a condition resembling leukemia in which the leukemic factor is absent, specifically the increase of leukocytes in the blood. The term was introduced by Cohnheim. Later, the concept of pseudoleukemia came to include various diseases of the hematopoietic organs that are clinically similar to leukemia, such as lymphosarcomatosis (see Lymphosarcoma), lymphogranulomatosis (see), diffuse hyperplastic processes in the lymph glands in tuberculosis, syphilis, etc. In other words, the concept of pseudoleukemia became collective, a 'miscellany' (Mischmasch), as Virchow expressed it. In recent times, the term 'pseudoleukemia' has almost completely fallen out of use, and when it is used, it is in the original sense of Cohnheim, i.e., as leukemia without the leukemic factor or as a prodromal stage of leukemia or as latent leukemia (Plehn), etc. However, for these cases, another term—aleukemia (see)—has now gained greater acceptance. Nevertheless, many researchers (Pappenheim, Tsypkin) raise the question of the extent to which pseudoleukemia (or aleukemia) can be derived from the concept of leukemia; in their opinion, the reverse should be correct; the basic concept should be pseudoleukemia, and leukemia is merely a consequence or a variant of pseudoleukemia precisely because the hyperplastic processes in the hematopoietic organs, and not changes in the blood, determine the essence of leukemia. Standing on this point of view, Tsypkin comes to a more general conclusion that ultimately all basic hematology reduces to pseudoleukemia, insofar as it deals with diseases associated with more or less diffuse hyperplastic processes in the hematopoietic organs or in the mesenchyme as a whole. Depending on where these hyperplastic processes develop (in the parenchyma or stroma of the hematopoietic organs) and what their cellular production is, various forms of pseudoleukemia arise: malignant anemia, polycythemia, lymphosarcomatosis, lymphogranulomatosis, Gaucher's disease, Mikulicz's disease, etc. Tsypkin's views have not gained universal acceptance, and the concept of pseudoleukemia is considered subordinate to the concept of leukemia (see).