Leukosarcomatosis

LEUKOSARCOMATOSIS, a term proposed by Sternberg to denote diseases of the hematopoietic and other organs, in which, on the one hand, one observes pictures of leukemia, and on the other, a peculiar proliferation of the sarcomatous tumor type from the same cells that flood the blood. The site of tumor development is most often the mediastinum (region of the thymus gland, pericardium, mediastinal pleura), the periosteum, rarely the skin, and the tumor usually does not have the character of a clearly defined node, but has a diffuse infiltrating growth. The color of such tumors is pale gray, more rarely gray-green (chloroleukosarcomatosis). Microscopically, one discovers a solid growth of round cells, of the grain-like type, and medium (more rarely small) lymphocytes, as is the case, for example, in round-cell sarcomas or in some lymphosarcomas; sometimes necroses and scleroses are noted. Nodes of similar structure, as well as diffuse infiltrates, can also be observed in other organs. Characteristic of the blood, along with rapidly progressing anemia (which distinguishes leukosarcomatosis from lymphosarcomatosis), is the appearance of a large number of large lymphoid cells, often constituting the overwhelming majority among white blood cells (large-cell leukemia). The disease is always fatal; the course is acute and subacute, for the most part several months. At the present time, all cases of leukosarcomatosis are classified as varieties of leukemia, specifically myeloblastic leukemias, in which, to one degree or another, tumor-like growth of myeloblastic hematopoietic tissue can also be observed (see Chloroma). It has also been clarified that leukosarcomatosis is not always large-celled, and on the other hand, the presence of large-cell leukemia by no means necessarily indicates the presence of tumor-like growth anywhere. Cases of banal leukemic blood with tumor-like growth have been described; however, in the presence of the latter, the leukemic factor may disappear completely (aleukemic leukosarcomatosis) or subleukemia is observed (subleukemic leukosarcomatosis). In the latter two cases, significant differential diagnostic difficulties arise in terms of distinguishing it from lymphosarcoma (see), which in the overwhelming majority of cases proceeds aleukemically. The combination of tumor-like growth with leukemic phenomena is thus not a sufficient basis for separating the corresponding cases into a special nosological unit with the name leukosarcomatosis. There is also no reason in such cases to speak of sarcoleukemias (Pappenheim), since the very process of tumor-like proliferations is currently classified not as true blastomas, resp. sarcomas, but as hyperplastic processes, analogous to the hyperplasias of hematopoietic tissue in leukemias. Cases of true lymphosarcomas with lymphocytosis in the blood have no relation to leukosarcomatosis (see also Leukemia).