Leukemia.

Synonym.—Leukocythemia.

Definition.—A constitutional disease, of unknown causation, and characterized anatomically by changes in the spleen, lymphatic glands, singly or combined, and accompanied by a marked increase in the white corpuscles and a decrease in the red.

History.—This rare, but peculiarly interesting disease, was first described by Dr. Hughes Bennett in 1845, and a few weeks later, though independently, by Virchow. Bennett, in holding an autopsy upon a man who died with a very much enlarged spleen and liver, found the blood filled with corpuscles resembling pus-cells, and yet there was no evidence of phlebitis, nor any reason to suggest pyemia, there being no local suppurative process. He therefore came to the conclusion that he was dealing with new pathological conditions in which pus-corpuscles were generated within the blood. He did not undertake to say, however, what relation, if any, the spleen and liver bore to the diseased condition.

A little later Virchow, independently, described a similar case, but declared that the corpuscles in question were not pus-cells, but white cells of the blood in very greatly increased quantities, and that there was a direct relation between the enlarged spleen and the increase of white corpuscles, and suggested the name leukemia. Bennett chimed priority of discovery, and named the lesion leukocythemia. Since then, much attention has been given to the disease, though but little light has been thrown upon the causation.

Varieties.—The older writers recognized two forms of leukemia—the splenic, in which the spleen was enormously enlarged, and the lymphatic, in which, while the spleen was somewhat involved, the chief characteristic was the enlargement of the lymphatic glands. These were for a time regarded as distinct pathological types, but since Neumann's discovery that the bone-marrow is the principal seat of the origin of the blood, especially of the leukocytes, and since it has been demonstrated that in both splenic and lymphatic leukemia the marrow-cells are involved, and that the spleen is enlarged to some extent even in the lymphatic form, the old division has been discarded, and that of Ehrlich and Lazarus has been generally accepted; namely, (1) Myelogenous leukemia (a growth of myeloid tissue); (2) Lymphatic leukemia (a growth of lymphoid tissue).

The Eclectic Practice of Medicine, 1907, was written by Rolla L. Thomas, M. S., M. D.