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PATHOLOGY OF NUTRITION. 



cells. They occur in serous membranes, skin, brain, breast, 

 and salivary glands. They are relatively benign, metastasis 

 being very rare. 



Endothelial sarcomata, or endotheliomata, are composed 

 of concentrically arranged cells, strongly resembling the 



FIG. 127. 



Melanotic alveolar sarcoma of the skin, a, mononuclear ; a', polynuclear sarcoma- 

 cells with epithelial character ; b, pigment-cells ; c, stroma with bloodvessels 

 and pigment. X 300 (Ziegler). 



endothelial cells lining the lymph-vessels and spaces from 

 which they have developed (Fig. 128). Degenerative changes 

 and subsequent calcareous infiltration give origin to the 

 so-called psammomata or "sand tumors" of the brain. 

 They occur in the pleura, peritoneum, and meninges of the 

 brain. 



Melanotic sarcoma is an exceedingly malignant variety 

 arising from pigmented tissues, such as the skin, choroid coat 

 of the eye, and pia mater. Its structure may be that of any of 

 the above varieties, though it is usually spindle-celled. The 

 secondary metastatic growths are likewise pigmented and 

 of similar structure. 



