TUMORS. 



523 



larynx. The horns and claws of the skin of the face and the 

 scalp of elderly persons are papillomatous tumors with very long- 

 and thin papillae. Warty tumors are known to be difficult to 

 cure, and with advancing age sometimes to change into cancer. 

 (I) Myxomatous papilloma occurs rarely on the skin, but more 

 frequently on mucous membranes. Such tumors consist of a 

 soft myxomatous connective tissue, always rich in blood-vessels, 

 and covered either with a comparatively thin layer of stratified 

 epithelia, or with a single layer of columnar epithelium. (See 

 Fig. 217.) 



FIG. 217. PAPILLOMA OF THE MUCOSA OF THE UTERUS. 



P 1 , papilla covered by a single layer of columnar epithelia ; PZ, epithelial layer in top- 

 view ; pz, papiUa deprived of its epithelial cover. Magnified 600 diameters. 



To this class belong the papillomatous tumors, so-called " carun- 

 eulae," of the female urethra, which are often extremely painful and 

 cause serious haemorrhages. They appear as dendritical, scarlet, 

 sessile vegetations, usually at the external orifice of the urethra. 

 They occur, but are rare, in the mucosa of the uterus and of the 

 bladder. Liicke first drew attention to the fact that the formerly 

 so-called " papillary cancer 77 of the bladder is originally a benign 

 papilloma, which in a secondary change may take on the charac- 



