QUESTIONS AND ANSWERS 145 



Tumors 

 Classify tumors and give an example of each class. 



Connective-tissue tumors, as fibroma and sarcoma. 

 Specialized tissue tumors, as epithelioma and adenoma. 

 Mixed tissue tumors, as dermoid cysts. 



Describe the pathologic difference between a malignant tumor and a 

 non-malignant tumor. 



Malignant Tumors. Jfon-Malignant Tumors. 



Non-circumscribed. Circumscribed. 



Infiltrate neighboring tissues. Do not infiltrate neighboring tissues. 



Rapid growth. Develop slowly. 



Spread by metastasis. Non-metastatic. 



Undergo degenerative changes. Seldom degenerate. 



Cachexia present. Cachexia absent. 



What is cancer? Name the varieties. 



Cancer or carcinoma is a malignant tumor made up chiefly 

 of epithelial cells. It is characterized by an infiltrative growth 

 and the formation of metastases. Three varieties: squamous epi- 

 theliomata, cylindrical epitheliomata, and glandular-cell cancers. 



What is melanosis? Give the cause of melanosis. 



Melanosis is an abnormal deposit of black matter in various parts 

 of the body. The color is due to the pigment melanin. This con- 

 dition, which is seen almost exclusively in old gray horses, is usually 

 associated with tumor formation. It is thought to be due to the 

 breaking down of red blood-corpuscles in the spleen and liver, 

 thus liberating melanin from the hsemoglobin. 



In what animals are melanosarcomata most commonly found? De- 

 scribe the gross appearance of melanosarcomata. 

 Horses, especially gray-colored ones. The tumors usually de- 

 velop in the region of the root of the tail and the anus, although 

 no tissue seems to be exempt. They appear as small nodules of a 

 soft or hard consistency and vary in size from that of a walnut to 

 a man's fist or larger. The cut surface is uniformly black or 

 dark-brown and soils the hands similar to shoe-blacking. 



Name the different types of sarcoma. What tissue does sarcoma 

 resemble? 

 1. Eound-celled sarcoma, 

 a. Small round-celled. 

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