388 ANDRE CROTTI 



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the cells of the thymus were polymorphic in character, and the Hassall's 

 corpuscles were mostly absent. In another child, nine months old, the 

 tracheobronchial glands were tuberculous. There was at the same time 

 a small cavern in the right lung. The thymus was caseous. The sclerotic 

 portions showed a marked polymorphism of the cells and a diminution of 

 the HassalPs corpuscles. In all these cases examined, the presence of 

 tubercle bacilli was made certain. 



Tuberculosis of the thymus may affect the miliary or the caseous type. 

 In miliary tuberculosis it is not uncommon to find a few small tuberculous 

 nodules throughout the thymic parenchyma. These tuberculous nodules 

 have no special significance except that they are only one phenomenon of 

 a generalized process. 



As seen in reviewing the literature, primary caseous tuberculosis is 

 very rare. Secondary caseous tuberculosis is more frequent. It is found 

 in connection with caseous tuberculosis of the mediastinal lymphnodes. 

 Often, however, in very advanced caseation of the mediastinal lymph- 

 nodes, one is rather surprised to find the thymus absolutely untouched. 



In leukemia and in Hodgkin's disease, the thymus seems to be usu- 

 ally uninvolved, although the mediastinal lymphnodes may be very hyper- 

 plastic. 



Tumors 



Primary tumors of the thymus are not as rare as they would at first 

 seem to be. As in many other organs, we find in the thymus, benign 

 and malignant tumors. 



Benign Thymomata. A lipoma has been reported by Wadde, Miinch- 

 meyer, and Miiller. A myxoma was described by Winogradow. 



Fibroma. In 1909, Winkler observed a case of atrophic cirrhosis 

 of the thymus in a thirteen-year-old child. The tumor was a large mass, 

 22% cm. wide, 9.8 cm. long, and about 2 cm. thick, hard, nodular in 

 surface, and attached to the neighboring tissues. The mass was removed 

 by operation after making a partial dissection of the sternum. It was 

 composed of connective tissue, more or less well organized, containing 

 foci of lymphocytes and fatty degeneration. Small, round figures re- 

 sembling Hassall's corpuscles were observed. Winkler regarded this as a, 

 fibroma. 



Dermoid cysts are rare. They may be uni- or multilocular, and con- 

 tain hair. No other foetal tissue is found. 



Cysts. Thymic cysts are rather rare. Two great varieties are found : 

 1st, the ciliated cysts; 2d, the cogenital syphilitic cysts. 



The ciliated cysts are present in human beings as well as animals. 

 They are lined with cylindrical, ciliated epithelium and are found in 

 fetus and new-born. They are usually located in the same portion of 



