ABSCESS, CYST, SINUS, FISTULA, AND POLYPUS 6i 



Serous Effusion. 



The term ' serous abscess ' is sometimes applied to a 

 circumscribed collection of serum under the skin. It is a 

 fluctuating swelling, and cannot always be differentiated 

 externally from a true abscess. It usually follows as a 

 sequel to a violent blow, and generally contains a blood-clot 

 or piece of bruised muscle tissue. The treatment is exactly 

 the same as with an ordinary abscess. An exploring trocar 

 or grooved needle, used cautiously, is very useful as an 

 additional aid to an exact diagnosis. 



Cysts. 



Definition. — A cyst may be defined as a soft, fluctuating, 

 non-purulent swelling containing a fluid or semi-gelatinous 



Fig. 37- — Exploring Trocar and Cannula. 



material which is secreted by the lining membrane which 

 surrounds it. It is sometimes due to the dilatation of an 

 obstructed duct, but is more often the result of degeneration 

 of the gland, as is shown by the microscopical examination 

 of the cyst wall and contents. 



Diagnosis.— It is sometimes difficult to distinguish between 

 a cyst and an abscess, as both fluctuate under the fingers ; 

 the chief distinguishing features are the absence of heat 

 and pain in the former, and the comparative slowness with 

 which it forms. A cyst, too, has well and sharply defined 



edges (see Fig. 38). 



Treatment.— The removal of a cyst is best effected by 

 carefully and completely dissecting around its external wall, 

 and so endeavouring to remove it m its entirety without 



