TUMORS. 325 



may become sarcomatous and thus a mixed tumor a sarcomatous eudo- 

 thelioma may be formed. 



The eiidotheliomata may be single, nodular, and of considerable size ; 

 or they may be multiple, numerous small tumors being scattered over 

 the surface of the part in which they grow. They may even form a 

 thick or thin pellicle over surfaces, or cause adhesions between adjacent 

 organs. They may form metastases. They occur in the dura mater and 

 pia mater, in the pleura and peritoneum, and have been described in the 

 skin, bone, gums, lymph-nodes, ovary, liver, brain, testicle, glandula 

 carotica, and salivary glands.' 



It is possible that as our knowledge of these tumors widens we may 

 be able to differentiate a group formed from the cells lining the great 

 body cavities peritoneum, pleura, and pericardium which are usually 

 called endotheliuin, but might, as is urged by Miuot, on account of their 

 origin and in distinction from the endothelium of the blood and lymph 

 vessels, etc., be more appropriately designated mesotheliuin. 8 



LIPOMA. 



Lipomata are tumors formed of fat tissue. The fat tissue occurs in 

 lobules and is similar to normal fat, except that the cells and lobules are 

 usually larger and less regularly arranged. There may be little connec- 

 tive tissue in the tumors, when they are very soft, almost fluctuating 

 Hpoma molle or there may be so much as to give the tumor considerable 

 firmness -fibro-lipoma. They may be in part transformed into mucous 

 tissue myxo-lipoma. Cartilage not infrequently develops in them, or 

 they may undergo partial calcification. 



Occasionally the blood-vessels are very abundant and dilated angio- 

 lipoma. They are usually sharply circumscribed, but may infiltrate sur- 

 rounding tissues. They are not infrequently pediculated. They some- 

 times grow to enormous size and may ulcerate. 



They are usually, isolated, but may be multiple. They are common 

 tumors, occurring usually in the subcutaneous or other fat tissue. They 

 may occur in the mucous membrane of the gastro-intestinal canal, in the 

 peritoneum, more rarely tn the dura mater, kidney, liver, and lungs. 

 They are benign tumors, not forming metastases; but they may be dele- 

 terious by ulceration or gangrene, and when not fully removed may ex- 

 hibit local recurrence. They may become sarcomatous. 



1 For a discussion of the endotheliomata consult : 



v. Volkmann, " Ueber endotheliale Geschwiilste." Deutsch. Zeits. f. Chirurgie, Bd. 

 xli., p. 1. 



Lnbarscli, "Ergebnisse d. allg. Path.," Jahrg. i., Abth. 2, p.-366; also "Endothe- 

 liom.," ibid., Jahrg. ii., p. 592. 



For embryological considerations bearing on the subject see : 



Glockner, Zeits. f. Heilkunde, Bd. xviii., p. 209, 1897. 



Marchand, Verh. der deutschen path. Gesellschaft, Bd. ii., p. 38, 1900. 



On the occurrence of giant cells and cells with very large nuclei in endothelioma, see 

 Glockner, Ziegler's Beitr., Bd. xxvi., p. 73, 1900. 



- For a consideration of the relationship between endothelium and mesothelium see 

 Minot, Science, March 29th, 1901, p. 489. 



