FIBRINOUS BRONCHITIS. 335 



purulent or purulent, and less tenacious, histologically resemb- 

 ling pus by reason of the large number of leukocytes present. 

 When the amount of this secretion is excessive, especially in 

 more chronic cases, the condition is known as bronchorrhoea ; 

 in some instances the odor of the sputum is very offensive 

 foetid bronchitis. 



Microscopically the bloodvessels are found to be dilated, and 

 surrounding them and infiltrating the walls of the bronchi are 

 numerous migrated leukocytes and young connective-tissue 

 cells. The epithelial cells of the mucosa are degenerated and 

 in many places desquamated (Fig. 146). 



Chronic bronchitis occurs most commonly in the aged, who 

 are often predisposed by reason of a passive congestion of the 

 lungs, due to some form of cardiac weakness. It may follow 

 a neglected acute attack or gradually develop after repeated 

 subacute attacks. It is also frequently associated with 

 emphysema or other diseases of the lungs, with gout and 

 Bright's disease, and, in children, with rickets. 



The bronchial walls are usually greatly thickened from new 

 connective-tissue formation in the outer fibrous coat. The 

 mucous membrane is generally atrophied ; the epithelial cells 

 are no longer columnar, but rounded or polygonal. In some 

 cases, however, the mucous membrane is swollen and hyper- 

 femic, and dotted with little gray points the mucous glands, 

 which are greatly enlarged. 



The cartilages of the bronchi and the muscular coat may be 

 so far supplanted by newly forming connective tissue as greatly 

 to weaken their walls. This in connection with increased 

 pressure from within, due to the increased expiratory efforts 

 of coughing, may cause fusiform or saccular dilatation of the 

 bronchi in places, bronchiectasis. 



Fibrinous bronchitis is a variety of chronic bronchitis in 

 which there are expectorated at intervals, during months or 

 years, branching fibrinous casts of the bronchi of a lobe. The 

 exact pathology of the affection is not understood. Similar 

 casts of the larger tubes may result from an extension of a 

 diphtheritic inflammation of the larynx or trachea. 



