Diagnosis.—Chronic leukamlia in the active stage can always be diagnosed by a careful examination of the blood. In periods of quiescence of the disease, how ever, the blood may, for a time, not sent the characteristic signs. It is the quality, rather than the quantity, of the leucocytes which characterizes leukwmia, though nearly all eases present a number of leucocytes never seen in the known forms of simple leucocytosis. In very rare instances the diagnosis from pseudo leukmmia and sarcoma may be sible. In children with secondary an mim, enlarged spleens, marked thmia, pronounced leucocytosis, and some myelocythmmia, the diagnosis from leukwmia presents at times great diffi culties. Acute leukremia resembles the purpurze of violent type, and the blood of all purpuric patients should be ex amined for leuksemia.
Blood of two cases of acute leukmmia examined. At a period of temporary im provement in one of the cases an ordi nary examination of the blood would have failed to discover any leukmmia; whereas by Ehrlich's methods, tile appre ciable percentage of typical myelocytes found would at once arouse suspicion, even in the absence of leucocytosis. Thayer (Johns Hopkins Hosp. B1111., May, June, '91).
In acute leukmmia anatomical lesions may antedate the changes in the blood by a considerable time. Kast (Deut. med. Woch., Oct. 29, '91).
The varied character of the leucocytes regarded as of the greatest importance in distinguishing between leucocytosis and leukmmia. The myelocyte of Ehrlich may be a valuable diagnostic feature, but one which is frequently wanting-. Troje (Deutsche med. Woch., Apr. 21, '94).
Case of leukmmia in which the impli cation of the lymph-glands occurred with, what is usually considered, a typical myelosplenic blood condition. It seems, therefore, that the blood-examination does not suffice to distinguish the types. Musser and Sailer (Trans. Assoc. Amer. Physicians, '96).
Case of lymphatic leuktumia in which the lymphocytes were found to contain sharply - circumscribed colorless bodies which showed amreboid movements even when cold. They were believed to be protozoa. IMannaberg (Centralb. f. innere Med., Apr. 25, '96).
There are only two forms of leukmmia: (a) Lympluernia; the blood shows an in crease of white cells of the type of lym phocytes. (b) Leukremia proper; the blood presents an increase of white cells of the type of leucocytes in the wider sense—cells presenting all possible vari ations between the size of the nucleus and the size of the cell-body. The increase of
the eosinophile-cells occurs generally only in leuktemia proper, exceptionally in lyin phmmia. The characteristic feature of the leukaemic blood as against that in leucocytosis is the polymorphism of the white cells. Weiss (Hamatologische Untersuchungen, Vienna, '96).
Acute leukmmia may be diagnosed by the occurrence of a rapidly-increasing anremia, with its accompanying symp toms, petechire over the body, or limmor rhages from the mucous ineinbranes, with enlargement of the lymph-glands, fever, and a moderately enlarged spleen and liver, accompanied by a decrease in the blood of the red cells and an increase of the white cells of mononuclear form. M. II. Fussell and A. E. Taylor (Phila. Med. Jour., Jan. 7, '99).
The distinction between acute and chronic leukaemia should be based upon the character of the onset; this in the acute form is always sudden, while in chronic leukremia, the same symptoms de velop late. These symptoms are weak ness and prostration, headache, stoma this, pains in the limbs, sometimes diffi culty in swallowing, liremorrhages in the skin and from the MUCOUS membranes, and sometimes hremorrhages into the brain. The blood shows a marked in crease of mononuclear leucocytes, nucle ated red corpuscles being rare. A. Den nig (Miinchener med. Woch., Sept. IS, 1900).
Etiology.—The etiology of the disease is probably concerned with a micro-or ganismal infection, the nature of which has not been determined; nor has the portal of infection been made out. For the numerous parasites of which a causal relation to leukaemia has been postulated no convincing pathogenicity has been demonstrated: they have, in all in stances, been examples of accidental or terminal infection. The morbid changes and the symptoms almost indubitably suggest an infection.
The conditions which influence the prevalence of the disease are obscure. Two-thirds of the cases are in males. The majority of cases occur after puberty and before the age of fifty. Cases have been seen in the very old, however, and in infants and even in the fcetus.
Intra-uterine transmission of lenkmmia from mother to child does not exist; but it still remains an open question whether or not an hereditary predisposition may be transmitted w hich may lead to the subsequent development of the disease. Saenger (Gaillard's Med. Jour., Sept., '90).