312 TUMORS. 



tissue, Jigo-w^wowwi; and they very frequently become sarcomatous, or 

 take part in the formation of very complex tumors. They may be dif- 

 fuse or encapsulated with fibrillar connective tissue ; they are frequently 

 very large, and may be multiple. Owing to the character of the base- 

 ment substance, the blood-vessels not infrequently rupture, giving rise 

 to larger or smaller hemorrhages within the tumor, or to the formation 

 of cysts. The cells are liable to undergo fatty degeneration. 



In the fibrous tissue of many tumors, in chronic inflammation of the mucous mem- 

 branes, variously shaped small cells occur whose bodies contain few or many well- 

 defined basophile granules which are not infrequently mistaken for cocci. Such cells, 

 called "mast cells," occur in various parts of the normal body. The nature of the 

 granules has not been definitely determined. 



Composed, as they are, of a type of tissue from which fat tissue is 

 developed in the embryo, the relations of myxomata to fat tissue are 

 very intimate. They are most frequently developed in, and probably 

 directly from, fat tissue. They are also found in the subcutaneous, sub- 

 mucous, and subserous tissue, in the marrow and periosteum ; in the 

 brain and cord ; in the sheaths and intrafascicular tissue of peripheral 

 nerves ; in intermuscular septa ; and in the interstitial tissue of glands, 

 such as the mamma and parotid. 



The myxomata are in general benign; yet they are very prone, espe- 

 cially the lipomatous forms, to local recurrence. They sometimes grow 

 very rapidly, and sometimes, though very rarely, form metastases. In 

 the not infrequent combination with sarcoma they may exhibit the most 

 marked malignancy. Some of the polypi of mucous membranes are 

 apparently myxomata or fibro-myxomata. On the other hand, many of 

 the so-called mucous polyps, those of the nose for example, are simply 

 oedematous hyperplasia3 of the mucosa. ' 



CEdernatous, loose, and cellular forms of fibrillar connective tissue 

 so closely resemble some of the forms of mucous tissue that certain 

 observers consider them identical. So prone are many tumors to un- 

 dergo mucous degeneration, and so frequent are the combinations of the 

 myxomata with other forms of tumors, that it is often difficult, some- 

 times impossible, to say whether the mucous tissue in a given composite 

 tumor is primary or secondary. 



SARCOMA. 



These tumors are formed on the type of connective tissue, but they 

 are, as a rule, largely composed of cells ; the basement substance, though 

 a constant and important factor, being much less conspicuous than in 

 adult connective tissue. They more closely resemble, in general, the 

 developing connective tissue of the embryo or the granulation tissue of 

 inflammation. 



The cells of the sarcomata are most varied in size. 



See reference to Wright, p. 467. 



