It is of special importance to study the changes due to certain intercurrent diseases in the blood picture of medullary leukæmia. This point has recently been the object of detailed investigation, in particular by A. Fraenkel, Lichtheim and others[35]. According to these authors, under the influence of febrile diseases the total number of leucocytes may be enormously decreased. The blood moreover is altered, so that the myelæmic characteristics become less marked, and the polynuclear neutrophil elements largely preponderate. The latter may attain the percentage numbers of common leucocytosis up to 90% and over.
We will here mention a few rare cases, demanding special attention, shewing the alterations leukæmic blood may undergo, and occasionally presenting almost insuperable difficulties in diagnosis. We find but a single case of this kind mentioned in the literature. Zappert reported a patient, who in February, 1892, had shewn the typical signs of myelogenic leukæmia. Amongst others the relation of white to red cells was found to be 1:4.92, and 1400 eosinophil cells per mm.^{ 3} (3.4%) were counted. At the end of September of the same year the patient was brought in a miserable condition to the hospital, where she soon died with gradually failing strength. During this period of observation the proportion of white to red was 1:1.5; the percentage of eosinophils, 0.43; the mononuclears, most of which had no neutrophil granulation, amounted to 70% of the leucocytes. Zappert expressly mentions that these mononuclear cells were in no way similar to the lymphocytes in general appearance. At the autopsy Zappert found the bone-marrow studded with non-granulated mononuclear cells, and the eosinophil cells were much more scanty than is usually the case in leukæmic bone-marrow. Blachstein, under Ehrlich's direction, investigated a second case of this kind. This patient had also been the subject of exact clinical investigations for some time on account of a myelogenic leukæmia. During the time he was last in hospital the blood could only be examined a day before the fatal termination, the direct consequence of a septic complication. With a markedly leukæmic constitution of the blood there were found 62% polynuclear cells, 17.5% mononuclear about the size of the ordinary myelocyte, 0.75% eosinophil cells, nucleated red blood corpuscles in moderate amount. The preponderance of polynuclear and the small number of eosinophil cells is readily explainable from the septic infection; on the other hand the absence of granules in the mononuclear cells is most surprising.