TUMORS. 369 



pretty uniformly throughout the growth, or they may be much 

 more abundant in some places than in others. The cells with single 

 nuclei, among which the giant-cells are found, may be of the 

 spindle-shaped variety, or they may be polymorphic, in which case 

 cells of various shapes and sizes are met with. 



The giant-cell sarcomata are usually derived from the medulla 

 of bone. They constitute the most common form of epulis (Fig. 

 333), and frequently attain very large dimensions when they take 



FIG. 333. 



Giant-cell sarcoma of the superior maxilla; epulis: a, large giant-cell, with numerous 

 nuclei ; b, tangential section of a similar cell. Aside from the giant-cells, the growth is 

 composed of spindle-cells and a moderate amount of a fibrous intercellular substance. 

 The tumor was removed from a man forty-one years of age, and was of slow growth, 

 having attained the size of a filbert in two and a half years. 



their origin in the marrow of the larger bones, such as the femur 

 or tibia. They are not, however, confined to bone, but may occur 

 in other situations ; e. g., the breast. 



The malignancy of giant-cell sarcomata must be estimated in 

 individual cases according to the principles already elucidated. 



/. MELANOSARCOMA. Sarcomata which spring from pigmented 

 tissues, such as the choroid of the eye, pigmented moles, etc., fre- 

 quently show a pigmentation of their constituent cells, the pigment 

 appearing as brown granules of various size within the cytoplasm 

 of the cells. The cells are not all equally affected, and many may 

 be seen without any sign of pigmentation. The tumors are apt 

 to be of the spindle-cell or large round-cell varieties, and are 



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