THE RESPIRATORY SYSTEM. 



481 



TUMORS. 



Primary tumors of the bronchi are rare. Lipoma, chondroma, and 

 fibroma have seen observed. Sarcoma is rare, but may occur, especially 

 in spheroidal cell forms, or as an extension of similar growths in the 

 mediastinum. Adenoma (Fig. 265) and primary carcinoma are rare. 

 Secondary carcinoma is not uncommon and may also involve the trachea 

 of the lungs. 



In chronic bronchitis, polypoid hyperplasiae, simulating tumors, may 

 project into the lumen. Ossification of the bronchial walls is of occa- 

 sional occurrence. 



LESIONS OF THE TRACHEAL AND BRONCHIAL LYMPH-NODES. 



The tracheal and bronchial lymph-nodes may be the seat of a variety 

 of lesions which, owing to their situation, as well as for other reasons, 



are of considerable practical impor- 

 tance. They may be enlarged from 

 hyperplasia in acute infectious dis- 

 eases ; by the development in them of 

 tumors; in leukaemia and with es- 

 pecial frequency in tuberculosis (Plate 

 III.). They may become pigmented 

 from inhaled coal or other dust and 

 may atrophy or become fibrous or 

 calcified. In cheesy degeneration fol- 

 lowing tuberculosis (Fig. 266), or in 

 suppurative inflammation, perfora- 

 tion may take place into the air 

 passages, or the pulmonary blood- 

 vessels, or aorta, or into the pericar- 

 dial or pleural cavities; in this way 

 haemorrhage or secondary inflamma- 

 tory processes or gangrene may occur. 

 Death may occur from pressure upon 

 the trachea by tumors of the adja- 

 cent lymph -nodes. Sudden death 

 from asphyxia may result from per- 

 foration into the trachea. Pressure 

 upon the pulmonary veins may lead 

 to pulmonary oedema. The bronchial 

 lymph-nodes are very important as 



distributing centres of infectious micro-organisms, and particularly as 

 31 



FIG. 266,-Tu 



CHIAL LYMPH-NODES. 

 The nodes are much enlarged and press upon 



the larger bronchi. 



