386 



HISTOLOGY OF THE MORBID PROCESSES. 



these cancers is probably induced by the proliferation of the epi- 

 thelium, but it sometimes happens that the fibrous tissue form- 

 ing the stroma of the tumor compresses the epithelium after the 

 growth has attained a certain stage of maturity, and causes an 

 atrophy of its cells (atrophying carcinoma). As a result the tumor 

 may suffer a diminution in size, but this shrinkage occurs only in 

 the older parts of the tumor ; the peripheral portions continue to 

 grow. It is no indication of a spontaneous cure. 



Carcinomata are malignant, but differ in the rapidity of their 

 clinical course. Those which are softer i. e., contain a larger pro- 

 portion of epithelium are of more rapid growth than the harder 

 varieties ; but they all tend to infiltrate their surroundings and are 

 liable to metastasis. The usual mode of infiltration is for the pro- 

 liferating epithelium to penetrate the lymph-spaces or lymphatic 

 vessels of the neighboring tissues. The cells may advance as solid 



FIG. 355. 



Carcinoma invading adipose tissue. The figure represents a section of the fat surrounding 

 the breast in a case of mammary carcinoma. Masses of epithelium are present in the 

 lymphatic spaces of the areolar tissue between the fat-cells. The nuclei of some of the 

 epithelial cells show imperfectly preserved karyokinetic figures. To the right, above, is 

 a group of four epithelial cells surrounded by a round-cell (inflammatory) infiltration. 



columns pushed out from the growth along these lymph-channels, 

 or cells may become detached from the main growth and be car- 

 ried by the lymph-current for a greater or less distance from the 

 original tumor, to find lodgement in some situation in which the 

 conditions may be favorable for their continued multiplication 



