PLEURITIS. 357 



PLEURITIS. 



Pleuritis, pleurisy or inflammation of the pleura, is nearly 

 always secondary to an adjacent inflammatory process, as 

 pericarditis, pneumonia, gangrene or tuberculosis of the lungs. 

 It may occur in the course of some general disease, as pyaemia, 

 septica3mia, typhoid fever, influenza, and other infectious dis- 

 eases, rheumatism, gout, and Bright's disease. 



Several varieties are usually described according to the char- 

 acter of the inflammatory exudate : fibrinous, serofibrinous, 

 and purulent. 



The fibrinous variety is generally confined to circumscribed 

 areas, though it may involve the entire pleura on one side. 

 At first the membrane is congested and its normal glistening 

 appearance is lost, due to the cloudy swelling of the endo- 

 thelial cells, the exudations and other phenomena character- 

 istic of the early stage of inflammation. The serous exudate, 

 rich in fibrin, coagulates in the form of a thin white pellicle 

 on the surface, varying in thickness in different cases. Where 

 opposed surfaces have become agglutinated, on separation 

 there is often a shaggy appearance somewhat similar to that 

 produced by pressing together the buttered surfaces of two 

 pieces of bread " bread-and-butter" pleurisy. 



Microscopically may be noted the dilated bloodvessels, sur- 

 rounding which and infiltrating the connective tissue are 

 numberless migrated leukocytes. The thin pellicle on the 

 surface of the pleura consists of a delicate network of fibrin- 

 filaments, containing in its meshes migrated leukocytes, red 

 blood-corpuscles, and possibly a few desquamated endothelial 

 cells, resembling thus very closely the alveolar exudate in the 

 stage of red hepatization of pneumonia. At this stage opposed 

 pleural surfaces, which are found adherent, can readily be sep- 

 arated. Later, however, on this temporary scaffolding of 

 fibrin a new connective tissue is built, through the agency of 

 the leukocytes and proliferating endothelial cells, which 

 results finally in firm fibrous adhesions. 



The serofibrinous variety may be simply a more advanced 

 stage of the inflammatory process. The quantity of the 

 serous exudate which accumulates in the pleural cavity varies 

 ereatly it may exceed four litres. 



