282 



Veterinary pathology. 



MYXOMA. 



Myxomata are tumors composed of mucoid connective tissue. 

 These tumors may be a subvariety of fibroma. Purely myxo- 

 matous tumors are not very common, occurring more frequently 

 in combination with other tumor tissue. They are usually found 

 in connective tissue, but in no special location. They have been 

 found in the heart, along nerve trunks, in the nostril, and a case 

 has been reported of a pure myxoma involving the entire orbital 

 structures in a horse. These tumors are usually about the size 

 of a hen's egg, rarely becoming very large, probably because of 

 their destruction bv degeneration. They are invariably single. 

 They appear as semi-solid masses, surrounded by fibrous cap- 

 sules and are usually dirty-white or gray in color. After they 

 are removed and an incision made into them a mucus or gela- 

 tinous, ropy fluid escapes. The cut section appears as a glassy, 

 semi-transparent, semi-solid mass and is very similar to Whar- 

 ton's jelly. The escaped fluid will be found by chemical test to 

 contain considerable mucin. Their blood supply is usually very 

 meager, in fact some authors regard myxomata as a mucoid 

 degeneration because of their limited blood supply. 



Microscopically, a myxoma is composed of stellate cells, in 



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Fi&. 142, — Section of Myxoma from the orbital fossa of a horse, 

 showing stellate cells. 



