350 HISTOLOGY OF THE MORBID PROCESSES. 



ata of the breast must not be mistaken for carcinomata, which 

 they superficially resemble when the glandular epithelium has 

 undergone atrophy due to pressure. In general appearance under 

 the microscope these fibromata resemble the outcome of a chronic 

 interstitial inflammation, but they do not seem to owe their origin 

 to an inflammatory process. 



Fibromata may undergo localized softening, due to fatty meta- 

 morphosis and necrosis. More frequently they are the seat of cal- 

 cification, the lime-salts being deposited in granules within the 

 intercellular substance, or in little globular masses, variously aggre- 

 gated. These calcified portions are apt to acquire a diffuse blue 

 color in sections that have been stained with hsemotoxylm. 



Mixed tumors, containing fibrous tissue and some other variety 

 of connective tissue, or smooth muscular tissue, are common. 

 Fibrosarcomata and fibromyxomata are liable to metastasis ; the 

 other mixed tumors and pure fibromata are among the most benign 

 of the tumors. 



2. Lipoma. Tumors composed of adipose tissue arise from pre- 

 existent fat, or from fibrous tissue of the areolar variety. Their 

 structure very closely simulates and is frequently indistinguishable 

 from that of normal fat (Fig. 312). But they reveal their inde- 

 pendence of the general economy by not being reduced in size 

 during emaciation of the individual. They sometimes enter into 

 the composition of mixed tumors, such as lipomyxomata, lipofibrom- 

 ata, and fibrolipomata. They often grow to considerable size, may 

 be multiple, but are not liable to metastasis and are benign. 



Calcification, necrosis, and gangrene may occur in lipornata, but 

 are usually confined to those of large size. 



3. Chondroma. The cartilage entering into the formation of 

 chondromata is usually of the hyaline variety, but sometimes fibro- 

 cartilages are also present, and may, in rare instances entirely 

 replace the hyaline form. The structure of the cartilages differs 

 somewhat from that of the normal types. The cells are less uniform 

 in character and in size, are more irregularly distributed through 

 the matrix, and are frequently embedded in the latter without an 

 intervening capsule. The tumor is rarely composed exclusively of 

 cartilage, but is usually nodular, the cartilaginous masses being sur- 

 rounded by a fibrous tissue in which the vascular supply of the 

 growth is situated. 



Chondromata generally arise from pre-existent cartilage, bone, or 



