EPITHELIAL TUMORS. 341 



Cysts (Cutaneous Tumors). A cutaneous tumor generally con- 

 sists of a closed sac or pouch, which is lined with epithelial cells, 

 and contains more or less liquid. Cysts are divided into several 

 varieties : 



Dermoid Oysts. These consist of cutaneous tissue, sebaceous 

 glands, sweat-glands, and hair-follicles forming in the centre a 

 pulpy-like sebaceous mass. Esser found dermoid cysts in the 

 ovaries. 



Retention Oysts. These are described as accumulations of sweat 

 in the glandular passages or follicles, as a consequence of an 

 obstruction of the canal at its exit. Atheroma originates as a 

 result of these accumulations in the sebaceous glands. They are 

 generally small, round cysts, lying in the skin, and filled with a 

 grayish- white, fatty, or pasty mass. Secretory accumulations in 

 the salivary glands cause mucous cysts or mucous polypi. These 

 are small formations having a soft, elastic feel externally, and 

 filled with watery or mucous secretions. In the large secretory 

 glands, when the canals of exit have become plugged up, we have 

 the formation of true retention cysts. There are two forms, called 

 the " honey-pouch" cyst and " glandular." These have already 

 been described (page 51). 



Extravasation Oysts. These cysts are developed in all loose 

 tissue, especially the cellular tissue under the skin; and in cases 

 where the inflammation is acute and the secretion becomes encysted 

 we generally find an accumulation of bloody, lymphatic fluid. 



The therapeutic treatment of cysts varies greatly, and depends to 

 a certain extent on their formation and location. Entire removal 

 is, of course, the best method, and this is generally adopted in 

 cases where the pouch or sac has been uninjured, while in cases 

 where the fluid has been allowed to escape it is almost impossible 

 to remove the follicle entirely. There are some cases where a sim- 

 ple puncture with a scalpel is effective. The puncture must be 

 followed by an injection of tincture of iodine for the destruction 

 of the cyst wall. Where we simply make an incision and evacu- 

 ate the sac, we clean it out and follow it up by applications of 

 creosote solution, oil of turpentine, tincture of cantharides, or 

 nitrate of silver solution (1 to 10), or we may "touch it up" 

 with the thermo-cautery. This, however, as a rule, takes a long 

 time to heal. 



