374 



Tumors. 



color. The minute structure of these enlarged glands corresponds 

 more or less closely to that of normal ones, but differentiation into 

 follicles, lymph cords and lymph sinuses is less marked, and the tis- 

 sue is more uniform. The tumor mass is made up of a finely fibrillar 

 or more coarsely trabecular network of connective tissue and blood 

 vessels in which are uniformly distributed, in close apposition to 

 each other, cells of the type of lymphocytes. In addition to the 

 small rounded lymphocytes with round nuclei rich in chromatin, 

 there may be found larger cells like those often met as early or 

 provisional forms in the germinal centers of the follicles, and once 

 and a while a few giant cells (Ribbert). Besides the proper lymph 

 nodes the follicles of the intestine, pharnyx, and especially the 

 lymphatic foci of the spleen, also undergo enlargement. The last- 



Fig. 106. 

 Malignant lymphoma in kidney of hog. 



named organ may reach very marked excess of volume, either show- 

 ing its Malpighian bodies increased to the size of a millet seed or 

 a pea (follicular hyperplasia of the spleen), or the whole pulp as 

 well evincing great increase of its lymphatic constituents as a 

 grayish-red swollen mass {diffuse splenic hyperplasia). 



In the course of the progressive proliferation the lymphatic 

 tissue passes beyond its original limits, the capsules of the lymph 

 nodes are broken through and the bunches of glands coalesce into 

 shapeless masses. Diffuse. extension takes place, the adjacent soft 

 parts becoming occupied by the penetrating lymphoma, and an infil- 

 trative type of enlargement is assumed from which the glandular 

 parenchymatous structures, like the liver and kidneys, may also 

 become diffusely and very markedly enlarged. The infiltrating 

 lymphoid tissue gives to the parenchyma of such parts a pale gray 



