362 



Tumors. 



Haemangiomata and Lymphangiomata. 



The hccmaugioiiia, or blood vessel tumor, is made up of dis- 

 tended and proliferated vascular tubes filled with blood, together 

 with the connective tissue supporting these vessels. Strictly speak- 

 ing, a true vessel tumor must consist for the most part at least of 

 vessels which have been newly formed, and should not be a tumor- 

 like enlargement made up simply of pre-existing vessels Avhich 

 have become enlarged from some pathological cause. It is, how- 

 ever, difficult to make a distinction between these two conditions, 

 partly possible only by examination of microscopic sections. There- 

 fore in a gross anatomical sense there is usually included under the 

 term hsemangioma, in a tentative way, a second variety which is 

 made up of blood lacunae, which give rise to a nodular irregularity 

 in shape and a spongy consistence of the part affected [caz'ernous 

 hcemangionia] . 



Fig. t)!). 

 Portion of cavernciis angioma of cow, seat of multiple thrombi. 



In man hsemangeiomata are represented first by the invariably 

 congenital blood-red or bluish-red, sharply outlined areas of skin, 

 in which the tissue of the cutis, often to the depth of the sub- 

 cutaneous fat, is filled completely with thin-walled bloodvessels in 

 a definitely limited area {Hccniangioma teleangicctaticum, ncc- 

 z'lis vascnlosus, Hammcus, vinosiis, wine mark). 



Such independent vascular tumors, caused by a disturbance of 

 tissue development, are, it appears, but rarely met in animals, prob- 

 ably because the pigment and hair of the skin conceals their pres- 

 ence. However, Leisering observed an angioma as large as a hen's 

 &gg in a dog, in the subcutaneous tissue (under surface of the tail) ; 

 Siedamgrotzky a similar one in a poodle, showing as a bluish-black 

 area through the skin ; Bonnet a fibroangioma as large as a child's 

 head with a strong connective tissue stroma in a horse, in the papil- 



