644 



THE URIXARY ORGANS. 



rhage, and they may be separated from the kidney structure by a fibrous 

 capsule. Such tumors are not rare in children. 1 



There are two principal varieties of these tumors, the papillary and 



the alveolar, which are, however, 



closely related. 



1. Papillary Adenoma. There 

 are cavities of different sizes, from 

 the walls of which spring branch- 

 ing tufts covered with cylindrical 

 or cuboidal epithelium (Fig. 407). 

 These tufts nearly fill the cavities. 



2. Alveolar Adenoma. There is 

 a connective-tissue framework en- 

 closing small round, oval, or tubu- 

 lar alveoli, lined or filled with 

 cells (Fig. 409). The cells are 

 usually large and may be cylindri- 

 cal, cuboidal, or polyhedral, and 

 may be pigmented in a manner 

 similar to the cells of the adrenals. 



Fatty degeneration of the epi- 

 thelium may be excessive and 

 glycogen may form in the cells of 

 these tumors. The stroma may 

 be present in considerable quan- 

 tity, the blood-vessels may form 

 conspicuous features, or a cystic 

 distention of the alveoli may 

 occur. Large areas may become 

 necrotic. They may form metas- 

 tases. 



Many of these tumors appear 

 to have developed from adrenal 

 cells astray in the kidneys, and 

 are then called hypernephroma (Figs. 405 and 408). 



The relationship between true adenoma of the kidney, adenomata 

 which appear to develop from strayed adrenal elements, and similar 

 tumors which are regarded by some observers as endotheliomata or endo- 

 thelial sarcomata, and certain forms of angio-sarcoma, is not yet alto- 

 gether clear. 2 



Primary carcinoma of the kidney is rare, adenoma being frequently 

 mistaken for it. Secondary carcinoma is not infrequent. 3 



1 See Engelken, Ziegler's Beitr., Bd. xxvi., p. 320, 1899, bibliography. 



2 For a study of hypernephroma of the kidney see Kelly, Phila. Med. Jour., 1898, 

 vol. ii., pp. 223, 283, bibl. ; see also summary by Thorndike and Cunningham, Boston 

 Med. and Surg. Jour., December 3d, 1903. 



3 For a careful study of tumors and other growths in the kidney see Kelynack, 

 "Renal Growths," 1898, bibliography; also references to bibliography, Busse, Vir- 

 chow's Arch., Bd. clvii., pp. 346, 377, 1898. 



FIG. 405. ADENOMA OF THE KIDNEY. 

 (Hypernephroma.) 



A tumor of the kidney formed from aberrant adrenal 

 tissue. 





