346 



TUMORS. 



196. This occurrence illustrates a congenital local predisposition to tu 

 mor formation. Simple congenital nsevi are sometimes mistaken for epi- 

 theliomata because of similarity in the gross appearance of certain forms. 



>;^Ka-rfeA 



FIG. 196. A PORTION OF A CONGENITAL NJSTUS OF THE SKIN. 



Such small na?vi are sometimes mistaken for epitheliomata and occasionally afford a starting-point for the 



latter. 



There are also carcinoniata of the skin, composed of cuboidal cells ar- 

 ranged in tubules or masses, which do not follow the type of the epithe- 

 lium of the skin, but rather that of the sweat glands or sebaceous glands.' 



FIG. 197. SMALL EPITIIELIOMA OF THE SKIN OF THE FACE. 



These tumors are found most frequently on the nose and eyelids, some 

 of them resemble eudotheliomata (Figs. 197 and 198). 



Sometimes certain of the cells in an epithelioma appear to coalesce, 

 forming a large multinuclear mass. This variety of epithelioma is some- 

 times called giant-cell epithelioma. 



Flexuer 2 has described a rare tumor arising from the epithelial layers 

 of the retina, which he calls a neuro-epilheUoma. 



Epitheliomata are apt to recur if not thoroughly removed, and may 



1 For a study of gland-like epitheliomata of the skin see Krompeclier Zieerler's 

 Beitr., Bd. xxviii., p. 1, 1900. 



2 Flexner, "A Peculiar Glioraa (neuro-epithelioma) of the Retina," Johns Hopkins 

 Hospital Bulletin, August> 1891. 



