LEUKEMIA 89 



normal numbers. With the decrease in numbers there is often a 

 change in the proportions of the varieties, the polymorphs being 

 relatively increased, so that the blood picture resembles that of 

 an inflammatory leucocytosis. 



Pathological anatomy and histology. The primary change is 

 found in the bone marrow which undergoes a cellular hyperplasia. 

 The red marrow of ribs, vertebrae, etc., usually is lighter colored 

 and of a firmer consistency. There is an extension of lymphoid 

 marrow in the shafts of long bones and an atrophy of fat. In long 

 standing cases there may be a considerable increase of connective 

 tissue. The hyperplasia consists of a marked increase in the finely 

 granular' myelocytes together with the eosinophilic myelocytes 

 and in lymphocytes, large mononuclear and polynuclear leucocytes 

 and nucleated red cells. 



The spleen is much enlarged. It is often rich in cells, sometimes 

 both follicles and pulp cords being equally increased, sometimes 

 one more than the other. The boundaries between them are less 

 distinct or are sometimes indistinguishable. The stroma is often 

 much increased, rendering the organ much more firm. In these 

 cases it is less rich in cells. The spleen pulp contains many mye- 

 locytes, finely granular and eosinophilic, and large non-granular 

 leucocytes, lymphocytes and polymorphs, in addition to which 

 nucleated red cells are also found. 



The liver is usually enlarged. The capillaries are widened and 

 contain many leucocytes. In the interlobular tissue and in the 

 lobules there is often a diffuse infiltrative growth and many 

 metastatic foci composed of myelocytes with lymphocytes and 

 polymorphonuclear leucocytes held in a meshwork of delicate 

 ground substance. Numerous cells, mainly myelocytes and lym- 

 phocytes, may be found undergoing mitotic division. 



The lymph glands show a cellular hyperplasia. The boundaries 

 of follicles and medullary cords are commonly apparent though 

 sometimes indistinct. The lymph sinuses and blood vessels con- 

 tain many leucocytes. The reticulum is sometimes thickened, 

 making the gland more firm. The follicles are composed mostly 

 of lymphocytes but also contain, especially in their peripheral 

 portions, finely granular and eosinophilic myelocytes, which are 

 especially abundant in the medullary cords. 



(2). In lymphatic or lymphoid leukemia the circulating blood 



