712 THE REPRODUCTIVE ORGANS OF THE FEMALE. 



eye. Even with the microscope it is often impossible to determine 

 whether small spheroidal or polyhedral cells which are not character- 

 istically grouped in these fibrous bauds are epithelial in character or not. 

 It is such cells, frequently left behind in other than thorough operations, 

 which give rise to local recurrence. 



The medullary and fibrous types are most common; the gelatinous is 

 rare. In any of these forms of cancer there may be cystic dilatations of 

 the' ducts and acini. Epithelioma may form at the nipple. Secondary 

 carcinoma of the mamma is rare. Retraction of the nipple is common in 

 later stages of fibrous types of mammary cancer (see Fig. 470). 



Cysts of the mamma seem to be for the most part retention cysts, 

 formed by the dilatation of the gland ducts or acini. During lacta- 

 tion such retention cysts are sometimes formed, and then contain milk. 

 They may reach an enormous size. At other times retention cysts are 

 formed containing serous or viscid, brownish fluid, which often exudes 

 through the nipple. These cysts may be large or small, single or multi- 

 ple. There, are usually at the same time some growth and induration of 

 the connective tissue of the gland. In some cases there are polypoid 

 outgrowths of connective tissue from the wall of the cyst. These cysts 

 are not to be confounded with the cysts which are developed with the 

 intracanalicular tumors, described above. 



