TUMORS 



481 



ened externally, and irregularly circular. They vary in size from a 

 small pea to the palm of the hand, are generally devoid of hair, their flat 

 surface being smooth, furrowed, or irregularly elevated. The skin 

 occasionally develops acne from pressure or alteration of the tissue. 

 Fibromata, both hard and soft, are not malignant. 



Many pathologists are not inclined to regard the callosities known 

 as bed or kennel tumors as fibromata. Most definitions of the term 

 tumor include the clause that thev are without demonstrable cause. 



Fig. 174. — Dependent fibroma. 



This would exclude these callosities, as their cause is obvious, usually 

 growing on prominent parts, exposed to friction and pressure whenever 

 the animal assumes the recumbent position. 



2. The Lipoma. — These fatty tumors of the subcutis are rarer than 

 fibromata. They are generally round or oblong in shape, very distinctly 

 circumscribed, being separated from the surrounding structures by a 

 layer of connective tissue. Sometimes they are of considerable size, 

 but as a rule they are of very slow growth, and often pedunculated or 

 lobular in outline and diffused in different directions. The mixed forms 

 of lipoma and fibroma (fibrolipoma) sometimes grow to an enormous 

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