Cholesteatoma; Papilloma. 383 



dog- an endothelioma originating from the spinal dura mater; 

 Kijnnemann a psammoma of the cranial dura mater about the 

 size of a duck's egg, overlying the anterior part of the brain in 

 a cow. Cholesteatomata have been found rather frequently in 

 the lateral ventricles in the horse ; met in this location they are 

 rounded, reniform nodes, varying in size from that of a lentil to 

 that of an egg, usually occurring bilaterally, a tumor suspended 

 from the choroid plexus in each ventricle. The surface is smooth 

 and shining, sometimes granular; the color white, gray or grayish- 

 yellow; the consistence about that of the liver, the cut surface 

 slightly gritty and the cholesterin recognizable in tiny opalescent, 

 shiny spots. Microscopically these tumors are made up of blood- 

 vessels, a loose connective tissue stroma and the endothelial ele- 

 ments, which have grown from the bloodvessel wall ; between 

 these cells, in the vessel walls and in the widened lumina of the 

 latter the cholesterin may be seen in the form of superimposed, 

 step-like plates with the borders broken out. In addition round 

 cells and pigmentary deposits may also be found. (Cornil and 

 Ranvier speak of the tumors in question as angiolithic sarco- 

 mata; Casper employs the term hsemangiosarcoma perivascu- 

 losum). 



[The position taken by the author in excluding from the 

 endotheliomata tumors originating from endothelium of the 

 large serous sacs, is not generally accepted ; and endotheliomata 

 of the pleura especially have been frequently described. 



Endotheliomata as a rule are slowly growing tumors and 

 although capable of metastasis are generally not marked by 

 many secondary formations. This, however, 'in some individual 

 examples is quite reversed and high metastatic malignancy is 

 manifested. So, too, in most cases they are not recurrent after 

 extirpation, but here again exceptions must be recognized. 

 They may occur as multiple primary growths. The subdivisions 

 above mentioned, cylindroma, cholesteatoma and psammoma. 

 are as a rule merely local growths, and arc among the least 

 metastatic forms of endotheliomata.] 



Papillomata. 



The name papilloma is applied as a comprehensive, even if 

 not well chosen, term for fibroepithelial neoplasms which occur 

 on the surface of the skin and mucous membranes in the form 

 of warty, conical, coralline, villous or nodular proliferations of 



