SARCOMA. 371 



place. It is certain indeed, that the capillaries are peculiarly 

 dilated in the softened parts, and project towards the cavities 

 corresponding to the old epithelial protrusions, forming a 

 number of closely aggregated loops. The secondary papillae 

 do not, as a rule, attain any great size; on the other hand 

 they are very numerous, spreading uniformly over the whole of 

 the ulcerated surface, or covering a great part of it in patches, 

 like sedge upon a moor. So far as I know, no cauliflower 

 growth of large size has ever been met with upon the surface of 

 a cancroid ulcer. 



h. Cicatrising epithelioma. This variety also is based 

 upon a peculiarity in the behaviour of the stroma — and that 

 after it has undergone infiltration. The skin of the face in 

 old people is occasionally the seat of a form of epithelioma in 

 which the infiltration never assumes any considerable propor- 

 tions ; it leaves no real ulceration in its train, but only a smooth 

 scar. As its extension is exclusively horizontal, and proceeds 

 from a single centre at a more or less uniform rate, it reminds 

 us of a patch of lichen on a tree ; hence its popular name of 

 ^^ rodent lichen" (Fressende Flechte). The point of histological 

 interest about it, to which also it owes its general aspect, is that 

 the residual stroma, which usually produces pus or papilloe, is 

 directly converted into a stiff cicatricial tissue, with a great 

 tendency to contract ; this remains coated with a thin layer of 

 epithelium. 



§ 315. Sarcoma of the skin exhibits certain peculiarities in 

 the mode of its development, which necessitate a comparison of 

 it with cutaneous epithelioma. Not the least important of the 

 services which VircJioiu has rendered to the subject of the sar- 

 comata, is his demonstration of the fact that cutaneous sarco- 

 mata very frequently originate at such points as are predisposed 

 thereto by other anatomical conditions. Among such local causes, 

 the soft, fleshy wart occupies as prominent a place, as the 

 hard wart, cauliflower excrescence, porrum, and cutaneous 

 horn do with reference to epithelioma. Those h;)^erplastic 

 conditions of the cutaneous sm'face therefore, in which the 

 connective tissue predominates, always tlu'eaten to pass into 

 sarcomata. Foremost among these are the soft, pigmented 

 warts (ncevus pigmentatus) \ this disastrous tendency has 

 long been known. They give rise, not to white, but to pig- 



