TUMORS. 285 



mass. The lacunae are not so distinct as those in normal cartil- 

 age, and their capsule may be absent. The intercellular substance 

 is usually homogeneous, as in normal hyaline cartilage, or it may 

 be fibrous, as in normal tibro-cartilage or elastic cartilage. The in- 

 tercellular substance becomes fibrous towards the margin of 

 the growth and finally forms a perichondrium. The cells may be 

 arranged in rows near the perichondrium, but they are more 

 likely to be irregularly distributed. The microscopic" appearance 

 of a degenerating, necrotic or mixed chondroma depends upon 

 the kind and extent of the condition existing. 



^^ Clinically, chondromata are usually benign, but they may be- 

 come i^alignant because of their extent. Some surgeons have 

 recorded-'.csses of metastatic chondromata. These tumi.irs are 

 frequentlydobulated and may be multiple. They have little ten- 

 dency to recur when removed. 



LIPOMA. 



Lipomata are tumors composed of adipose tissue with a con- 

 nective tissue framework supporting the vascular supply. They 

 occur quite commonly in the horse, ox, and dog, but none of the 

 domestic animals are exempt. They usually develop where adi- 

 pose tissue normally exists, as the subcutaneous tissue, submu- 

 cosa and subserosa, omentum, etc. They mav also occur in tissue 

 that contains no fat, as the liver, kidney and even the brain. 

 The}- occur most frequently in the subcutaneous tissue in the 

 horse ; in the intestinal and omental subserosa of the ox and 

 hog; in the subcutaneous and conjunctival submucosa in the 

 dog, and in the uterine submucosa of the sheep and the cow. 



Lipomata are usually circumscribed, but thev mav be diffuse. 

 The accompanying cut is from a photograph of a two-vear-old 

 colt in which there is shown a diftuse subcutaneous lipoma of 

 the left hind leg. These tumors mav liecome enormous in size 

 in the horse and ox, some cases having been reported of lipomata 

 as large as a ^\-ash-tub and weighing 30 to 7<i kilograms (66 to 

 154: lbs.). In consistency, these tumors ma\- be firm and dense 

 or soft and flabby. The^• are usuallv surrounded bv a fibrous 

 capsule and in section those from the peritoneum and omentum 

 ere vello-\\'ish or white in color. Peritoneal, omental, submucous 

 and subcutaneous lipomata have a smooth surface ; intestinal 

 lipomata are usually lobulated. Bands of connective tissue may 

 divide the tumors into lobes or lobules or the connective tissue 

 may be dilTuse throughout the entire structure. In cutting a 

 lipoma the resistance varies according to the quantity of fibrous 

 connective tissue it contains. If osniic acid is applied to the free 



