TUMOKR. 347 



form rnetastases, but in general they are the least malignant of the car- 

 ciuomata. Some of the smaller forms may exist for years with no evi- 

 dent tendency to growth (Figs. 197 and 198). 



Cylindrical-celled Carcinoma. These tumors, closely allied to some 

 forms of adenoma (see Fig. 184), occur in the stomach, intestines, and 

 uterus. The cells may be only in part cylindrical, the remainder having 

 various shapes, and all being loosely or closely packed in larger or smaller 

 alveoli. They may have much or little stroma. They merge impercept- 

 ibly into the next class : 



Carcinoma Simplex. These, which are by far the most frequent of the 

 carcinomuta of internal parts, are characterized by the alveolar structure 

 and by the absence of any special characteristic shape in the cells, which 



FKJ. 198. -S 



may be spheroidal, polyhedral, fusiform, or cuboidal. They may or 

 may not resemble the epithelium of the gland in which they originate. 

 They are usually nodular tumors, and may be hard or soft. If the new- 

 formed stroma is abundant and der.se, and preponderates over the cellu- 

 lar elements, the tumor is usually hard and is called scirrhtts or fibro- 

 carcinoma (Fig. 199). If. on the other hand, the cellular elements largely 

 preponderate, the tumor is usually soft, and, if it do not contain too 

 many blood-vessels, may have a general resemblance to brain tissue, and 

 is then called encephaloid or medullary cancer ; or, better, Carcinoma molle 

 (Fig. 182). These are among the most malignant of the carciuomata. 



FIG. 199. FIBRO-CARCIXOMA OR CARCINOMA DURUM (SCIRRHUS CARCINOMA). 



The intercellular tissue in these carcinomata may become so abundant 

 as nearly to obliterate the cellular elements, but it is doubtful if they 

 ever undergo spontaneous cure in this way. These tumors may be hard 

 iu one portion and soft in another. They may contain many blood- 

 vessels, C. telangiectoides. They occur as primary tumors in the mamma, 



