522 



TUMORS. 



been set up. Under these circumstances, an originally benign 

 papilloma may pass into a myeloma, or a secondary change into 

 cancer may take place, both rendering the tumor malignant. 

 According to the nature of the connective tissue and the amount 

 of covering epithelium, we distingiiish a horny and a myxoma- 

 tous papilloma as primary tumors. 



(a) Horny papilloma is composed of highly vascularized 

 fibrous connective tissue, producing branched, finger-like pro- 

 longations, and is covered by a stratified epithelial layer, usually 

 of considerable breadth. The deepest layers of the epithelia con- 

 tain a varying amount of pigment. (See Fig. 216.) 





FIG. 216. PAPILLOMA OF THE LARYNX. 



E, heavy epithelial cover; P, papillary prolongations of connective tissue ; V, wide blood- 

 vessels. Magnified 50 diameters. 



Warty tumors are of frequent occurrence on the skin, partic- 

 ularly of the fingers, and are often caused by a continued local 

 irritation of the part. They usually appear at the time of 

 puberty, and disappear spontaneously. They attain the largest 

 size in the region of the genitals, and are called in this situation 

 warty condylomata, their growth being always due to the local 

 irritation produced by the blennorrhoic secretion. They have 

 nothing in common with syphilis. Warty tumors are also of 

 frequent occurrence in the mucous membranes, especially of the 



