MYELOGENOUS OR LEUCOCYTIC LEU K/EMIA.—By myelogenous or leueocytic leukwinia we understand the type in which the hyperplasia affects the mye loeytes of the marrow and the leucocytes derived from them. It is the common type. The essential change in the mar row is the so-called pyoid. condition, a marked overgrowth of the myelocytes, which more or less completely replace the fatty marrow. Microscopically the tis sue is chiefly composed of neutrophilic myelocytes, whicb in properly prepared preparations are seen to be in active production and development into trophilic polymorphonuclear leucocytes.
The eosinophilic myelocytes are also in actual excess, and mast-cells may often be seen in large numbers. The osteo plaxes are in excess, and are actively en gaged in phagocytic function and con tain erythrocytes and leucocytes. The lymphocytic nodes of the bone-marrow are not affected in the process of over growth.
The secondary lesions in the marrow consist, for the most part, of alterations in the erythrogenetic tissues. There is a marked toxic heemolysis connected with the condition, and in the attempt to keep pace with the destruction of the red cells the red marrow undergoes a compensatory hypertrophy, it becomes splenified like the fcetal marrow, just as in pernicious anTmia. This red marrow may be universal, or may appear only in scattered areas; in some cases it is en tirely absent. Microscopically the red marrow presents myriads of enucleated red cells engaged in active proliferation, the macroblasts being especially promi nent. Hemorrhage and infarction may be present, as may fatty degeneration and hyaline changes.
Case of more or less pure myelogenous leukmmia. The spleen weighed 10 ounces, but the lymph-glands were not at all enlarged. Beatty (Dublin Jour. of Med. Science, May, '91).
The myeloeytes are identical with mar row-cells, and are present in increased amount because of some abnormal ac tivity in cellular proliferation in the mar row. Stanley (Birmingham 111ed. Re view, Jan., '94).
The marrow-changes are, as a rule, the first and the essential, though subse quently often overshadowed by the splenic and lymphatic manifestations.
Boyd (Practitioner, Aug., '94).
Case of inyelogenir leukemia in which erythrocytes presented numerous mitoses. Pick (Berliner klin. Woch., No. 43, '94).
In acute leukaunia there are karyo kinetic changes ill leucoeytes, besides great number of them. Marrow of long bones showing hyperplastic multiplica tion of medullary elements, that of ribs containing small number of nucleated red corpuscles. Possible indication that evolution of young lymph-cells into red corpuscles impeded. Askanazy (Vir chow's Archiv. B. 137, II. 1, '95).
The alterations in the blood correspond to those in the marrow. The white cells number usually from 100,000 to 600, 000 per cubic millimetre. Neutrophilic myelocytes constitute a large portion of the circulating white cells, sometimes more than half. Next in number are the neutrophilic polymorphonuclear leuco cytes. Mononuclear eosinophiles (mye locytes) and polymorphonuclear eosino philes are in most cases present in large numbers. The non-granulated large mononuclear cells are usually in excess. Mast-cells are seen in considerable num bers. Many of the cells of all the enu merated types present a marked polymor phism in size, shape, and appearance of nuclei; and in the number, size, and staining of the granules they vary greatly; this extreme degree of polymor phism is characteristic of leukemia. Cellular degenerations often affect these leucocytes, karyolysis being more fre quent than karyorrhexis. The lympho cytes are usually not increased in mye logenous leukmmia: if in excess it is to a slight degree, dependent probably upon the antumia, and the cells do not present the polymorphism and degenerations seen in the leukmmic corpuscles. Cell division is rarely to be seen.
Case of spleno-rnyelogenous leukmmia, not remarkable except for the blood count at the first examination. There were 260,000 leucocytes. SS0,000 red cor puscles, and 30 per cent. of hcemoglobin. Brannan (Amer. Medico-Surg. Bull., May 15. '94).