370 



Tumors. 



uncommon thing for good histologists to make use of different 

 diagnostic terms to describe one and the same tumor, one perhaps 

 calHng it sarcoma, others endothehoma, perithelioma or alveolar 

 sarcoma. This is but natural when one considers the number and 

 variability of connective tissue tumors and their combinations, the 

 differences of composition which exist in different parts of one indi- 

 vidual growth and the changes and metaplasias which are possible, 

 these features preventing any schematic and clearly defined classi- 

 fication. 



The macroscopic appearances of sarcomata are naturally very 

 variable on account of the many types of histological structure 

 which they may present. Some are soft, others hard ; their color is 

 generally a grayish-white, similar to the tissue of lymph glands or 

 foetal brain tissue (hence the old terms medullary sarcoma and 

 encephaloid sarcoma). They are usually rapidly growing tumors, 

 some growing in nodular, nodal or lobulated forms, others as infil- 

 trative growths. Their expansion not only occasions considerable 

 pressure upon the surrounding tissues and organs, but by stretching 

 the tissues they approach the surface of the organ, break through 

 the mucous membrane or external skin, or destroy the part from 

 which they arise by their deeper growth. By their infiltrative 

 growth and penetration between the tissues sarcomatous formations 

 occaeion marked enlargement in bulk and expansion of the part 

 aft'ected. Isolated tumors, reaching from five to seventeen kilograms 

 in weight, and enlargements of organs of perhaps twice or three 

 times the normal size, are not uncommon in sarcomatosis of the 

 kidneys, liver, rectum, spleen and lymph glands. The great tendency 

 to infiltration occasions daughter nodes in the vicinity of the orig- 

 inal growth and leads to metastases, which are especially likely to 

 follow the blood current. Penetration into blood vessels is often 

 apparent to the unaided eye in case of large veins, as those of the 

 liver. The tissue increase, both in the orimarv and secondarv 

 tumors, is always due to the independent proliferation of the sar- 

 coma cells, the formation of blood vessels (associated prolifera- 

 tion), however, proceeding directly from the organ in which the 

 sarcoma cells are distributed, apparently from a peculiar influ- 

 ence exerted by the tumor cells upon the endothelium (Ribbert). 

 These vessels, proliferating in association with the tumor cells, for 

 the most part maintain their capillary type, often, of course, as 

 wide endothelial tubes ; the frequence of haemorrhage in the sar- 

 coma substance being due to the thinness of their walls. Because 

 of this abnormality in the blood supply, which may not keep pace 



