Histology of the Blood, Normal and Pathological

by Paul Ehrlich; Adolf Lazarus

2. leukæmic processes with proliferation of myeloid tissue:

"myelogenic leukæmia."

The accompanying clinical phenomena may be indicated by simple unequivocal amplifications, for instance, "lymphatic leukæmia with enlargement of the spleen or of the liver"; "myelogenic leukæmia with enlargement of the lymph glands," &c.

From our present knowledge, which, it may be remarked, is still far from full, we may assume that lymphatic and myelogenous leukæmia have quite a different ætiology. The recent discovery of Löwit should be decisive on this point, for he demonstrated in myelogenic leukæmia the presence of forms like plasmodia within the white blood corpuscles, but was unable to find them in lymphatic leukæmia.

The necessity of separating lymphatic from myelogenic leukæmia is further shewn by the fundamental clinical differences between them.

Lymphatic leukæmia falls clinically into two readily distinguishable forms. In the first place acute lymphatic leukæmia, characterised by its rapid course, the small splenic tumour, the tendency to petechiæ and to the general hæmorrhagic diathesis. By its startling course this disease has given all observers the impression of an acute infectious process.

The second form of lymphatic leukæmia is marked off from the preceding by its chronic, and often very protracted course. The spleen shews its participation in the disease, as a rule by very considerable enlargement. We have at present no investigations adequate to decide whether chronic lymphatic leukæmia represents a single disease, or should be etiologically subdivided. Hæmatologically, all lymphatic leukæmias are characterised by a great preponderance of lymph cells, in particular of the larger varieties. It should here be expressly mentioned, that richness of the blood in large lymph cells, is by no means characteristic of the acute form of leukæmia, for chronic, very slowly progressing cases shew the same condition. Thus in a case of this kind under observation in Gerhardt's wards, all observers (Grawitz, v. Noorden, Ehrlich) found the large cells during its whole course. In agreement with our remarks elsewhere (see p. 104), we assume with regard to the origin of lymphatic leukæmia, that the increase of the lymph cells is brought about by a passive inflow into the blood; and not by an active emigration from chemical stimuli.

Myelogenic leukæmia presents a picture that is different in every particular. In former years the distinction between myelogenic leukæmia and simple leucocytosis offered great difficulties. These conditions were regarded as different stages of one and the same pathological process, and when the proportion of white to red corpuscles exceeded a certain limit (1:50) it was said that leucocytosis ceased, and leukæmia began. By the aid of the analytic colour methods the fundamental difference between the two conditions was first disclosed. Leucocytosis is now recognised to be chiefly an increase of the normal polynuclear neutrophil leucocytes; whereas myelogenic leukæmia brings elements into the blood that are abnormal. The cells here introduced are so characteristic as to render the diagnosis of leukæmia possible, even in the very rare cases where the total number of the white blood corpuscles is not to any extent increased. The best example of which we are aware is a case observed by v. Noorden, in which the proportion of white to red was only 1:200.

Although the blood picture of myelogenic leukæmia has been so clearly drawn by Ehrlich, misconceptions and obscurities still occur in the literature. And they are due to great errors in observation. It has for instance happened that unskilled observers have regarded and worked up cases of lymphatic leukæmia as myelogenic. The apparent deviations discovered in this manner are copied, as specially remarkable, from one book to another. Through insufficient mastery of the staining method, the characteristic and diagnostically decisive elements (neutrophil myelocytes for example) are frequently mistaken. A further source productive of misconceptions lies in the circumstance that the typical leukæmic condition of the blood may essentially change under the influences of intercurrent diseases. Thus the intrusion of a leucocytosis, brought about by secondary infection, is able to obliterate more or less the specific character of the blood. Such conditions must naturally be considered apart, and should not be used to overthrow the general characteristics of the picture. No one surely would deny the diagnostic value of glycosuria for diabetes, because in conditions of inanition, for instance, the sugar of a diabetic may completely vanish, although the disease continues. And one does not deny the diagnostic value of the splenic tumour in typhoid fever, because the enlargement of the spleen may occasionally subside, under the influence of an intestinal hæmorrhage.

From these considerations it is obviously necessary to derive the description of leukæmic blood from pure uncomplicated cases; and to construct it with the aid of standard methods. In this manner a type is obtained so characteristic, as to render diagnosis absolutely certain from the blood alone.