342 TUMORS. 



The carciiiomata are, as a rule, malignant tumors, but the different forms 

 vary much in this respect. 



Carciiiomata are liable to fatty, colloid, mucous, and amyloid degen- 

 eration, and are especially prone to ulceratiOn (see Fig. 185), to haemor- 

 rhage and inflammation (Fig. 190). They may become partially calcined, 



FIG. 190. EXUDATIVE INFLAMMATION IN CARCINOMA. 



Showing leucocytes in the stroma and in the epithelium. The epithelium is disintegrating, and in the 

 small region shown in the cut the leucocytes are apparently acting as phagocytes in the softening and re- 

 moval of the disintegrating epithelium. 



and are not infrequently combined with other forms of tissue in the 

 mixed tumors. 



They are more frequent in the middle-aged and elderly than in the 

 young, but they may occur at any age. 1 Multiple primary carciiiomata 

 have been occasionally reported. a 



FORMS OF CARCINOMA. 



In certain carciiiomata of the skin and mucous membranes, the cells, 

 following the type of epithelium from which they arise, as they grow 

 older are apt to become flattened or squamous ; these tumors are called 

 Siuamous or Flat-celled Carcinomata, or simply Epitheliomata. In another 

 class of tumors, such as frequently occur in the gastro-intestinal canal 

 and uterus, the cells are more or less cylindrical in shape, forming a 

 palisade-like lining to the irregular alveoli; such tumors are called 

 Cylindrical- celled Carcinomata, although here again many of the cells are 

 not cylindrical at all, but may have a great variety of forms. There is 

 a third and very common form of tumor, in which the epithelial cells 



1 For a statistical summary of carcinoma cases, with bibl., see Riechelmnnn, Bcrl. kl. 

 TVochenschr., August 4th and llth, 1902. 



8 See Warthin, Jour. Am. Med. Assn., May 6th, 1899, bibliography. 



