372 MORBID ANATOMY OF THE SKIN. 



mented sarcomataj so that the local predisposition extends its 

 influence even to a collateral circumstance like this. Tumours 

 which spring from soft Avarts usually continue to betray their 

 origin for a long period, even in their broader outlines — pre- 

 senting themselves in the form of true ''fungi," i.e. true mush- 

 room-like proliferations, with a broad base and overhanging- 

 edges. But even in tumours of large size, their origin from 

 the papillary body may soon be established by minute examina- 

 tion also. The cutis proper extends unaltered beneath the 

 tumour ; and this even where it is displaced and dragged into 

 the pedicle. 



Again, scars predispose to the development of sarcomata. 

 The sarcoma of scars is also known as '' false keloid." By tho 

 term Keloid, Alihert denotes a scar-like tumour of the skin. It 

 forms oval protuberances of a red colour and tough consistency, 

 often with claw-like prolongations ; its surface is smooth, and it 

 is usually found in parts of the skin which were previously 

 healthy. The tissue may be termed sarcomatous, and the 

 arborescent distribution of the growth is ascribed by Collins 

 Warren (Sitzb. d. K. Akadem. d. Wissensch. Bd. Ivii., 

 1868) to its localisation round the smaller arteries of the cutis. 

 It is otherwise with the false keloid. This may be said 

 rather to replace a scar than to grow out of one. In the regular 

 course of the development of a scar, the presence of round-cell 

 and spindle-cell tissue is only provisional ; they speedily give 

 place to fibroid tissue. Now if either the one or the other 

 element persists longer than its proper time, and if it accumu- 

 lates in disproportionate amount, we get, instead of a scar, a 

 tumour belonging to the sarcomatous series. Even fungous 

 granulations (§ 105) may be viewed in this light ; and they form 

 one extreme of a series of transitional forms, whose other extreme 

 is represented by the most luxuriant and malignant sarcomata. 



In addition to the above, Virchow has directed attention to a 

 local cause which determines the formation of many cutaneous 

 sarcomata. Eepeated irritation and inflammation is one of the 

 most frequent and eflicient excitants of sarcomatosis ; another 

 proof that our comparison of the sarcomata with the products of 

 inflammatory proliferation rests on a deeper foundation than the 

 mere form of the cells {Virchow, Krankh. Geschwulste, Bd. ii. 

 p. 246, seqq.). 



