392 AKDKE CKOTTI 







Spindle-cell sarcoma has been encountered ; it takes its origin from 

 the connective tissue of the thymus gland. Such a case was reported 

 by Gabcke, in 1896, although he failed to demonstrate the presence of 

 HassalPs corpuscles. 



In 1892, Schneider reported a case of fibrosarcoma of the thymus 

 without, however, having absolute proof that the tumor was of thymic 

 origin as no HassalPs corpuscles were reported. The cells were of the 

 round cell type and the connective tissue was quite marked. 



In 1898, Ertmann reported a large cell sarcoma' of the thymus in a 

 man forty years old. The tumor filled the anterior mediastinum and ex- 

 tended as far upward as the thyroid. Xo HassalPs corpuscles were found. 



In 1903, Torri reported a case of myosarcoma of the thymus in a 

 woman fifty-six years old. The tumor was rather firm, lobulated, oc- 

 cupying the anterior mediastinum. The microscopical examination showed 

 the tumor to be composed of lymphoid cells, small, round-cell sarcoma, 

 and large cells resembling fibromuscular cells. Furthermore, numerous 

 HassalPs corpuscles were present. The origin of these fibromuscular cells 

 is rather difficult to understand unless they should be related to the myoid 

 cells which may be encountered in the thymus. 



Carcinomatous Thymoma. This type appears to be formed of 

 cylindrical or cubical epithelium lying in dense connective tissue. In 

 some cases the cells are chiefly cubical and arrange themselves in con- 

 centric layers whose structure resembles the HassalPs corpuscles. In some 

 instances they show typical alveoli, hence, the name, too, of alveolar car- 

 cinoma, 



Carcinoma of the thymus may be classified as, 1st, epithelioma of 

 the Malpighian type ; 2nd, medullary carcinoma. This classification is 

 made according to the predominating type of cells present in the tumor. 



In the epithelioma the cells composing the growth are generally some- 

 what large and resemble those seen in the Malpighian layer or stratum 

 mucosum of the skin. Letulle mentions mucoid degeneration of the cells. 



The carcinomatous thymoma takes its origin, most likely, from em- 

 bryonic residues of the thymopharyngeal duct, or from the reticular cells, 

 or from the HassalPs corpuscles. 



Mixed Malignant Thymomata. Xot so uncommonly both types of 

 tumors are mixed together, as in the thyroid. They present histologically 

 the characteristics of sarcoma and carcinoma combined. 



