698 VI. OCCURRENCE OF LIPIDS IN THE ANIMAL 



of neutral fat is present. The absence of appreciable amounts of neutral 

 fat distinguishes the xanthomas from depot fat. 923 The cholesterol usu- 

 ally occurs largely in the form of the esters. 918 ' 920 ' 923 An analysis of speci- 

 mens of xanthomatous tissue obtained from skin by Ciaccio 924 was as 

 follows: total lipids, 11.1%; phospholipids, 0.63%; free cholesterol, 0.98% ; 

 total cholesterol, 2.0%; and neutral fats, 7.74%. 



(a) Primary Xanthomatosis. According to Thannhauser and Schmidt, 922 

 there are two types of primary xanthomatosis. In the first class, 

 referred to as primary essential xanthomatosis of the hypercholes- 

 teremic type, the following sub-groups are listed: (1) xanthelasma of eye- 

 lids and xanthoma tuberosum et planum; (2) tendon xanthoma; (3) 

 xanthoma tuberosum et planum and tendon xanthoma; (4) xanthoma of the 

 blood-vessels and endocardium; (5) forme frusle of essential xanthomatosis; 

 and (6) xanthomatous biliary cirrhosis. In this first category, an accumu- 

 lation of cholesterol obtains in a transparent clear serum, but the neutral 

 fat is normal. 925 Lipid phosphorus is high. Serum cholesterol values as 

 high as 600 milligram per cent have been reported, but the proportion of ester 

 to alcohol is normal. 917 ' 918 - 925 ' 926 In this type of xanthomatosis, the deposi- 

 tion of lipid appears to have a predilection for tendons, skin, and subcutane- 

 ous tissue. It differs from other types of xanthomatosis in that it does not 

 respond to diet. 917 - 918 ' 927 It is believed that the increased cholesterol reflects 

 an increased synthesis of this sterol, together with an imbalance in the 

 excretory mechanism for the substance. 



The second division of primary xanthomatoses is designated by Thann- 

 hauser and Schmidt 922 as primary essential xanthomatosis of the normo- 

 cholesteremic type (eosinophilic granuloma) . In turn, -it is divided into the 

 following categories : (1 ) xanthoma disseminatum of the skin ; (2) xanthoma 

 disseminatum and diabetes insipidus; (3) osseous xanthoma; (4) Schiiller- 

 Christian's syndrome; and (5) generalized xanthoma of the normo- 

 cholesteremic type. As one would surmise from the title of this sub- 

 division, normal cholesterol as well as normal lecithin and normal neutral 

 fat occur in the serum in xanthomatosis of the normocholesteremic type. 



(b) Secondary Xanthomatosis. This type of xanthomatosis is character- 

 ized by a hyperlipemia, which may contribute to its formation. The level 



923 A. Chanutin and S. Ludewig, J. Lab. Clin. Med., 22, 903-911 (1937). 



924 I. Ciaccio, Bol. soc. ital. biol. sper., 19, 225-227 (1944). 



925 E. B. Man, unpublished observations; cited by J. P. Peters and D. D. Van Slyke, 

 Quantitative Clinical Chemistry, vol. I, 2nd ed., Williams & Wilkins, Baltimore, 1946, p. 

 541. 



928 G. Klatskin, New Intern. Clinics, [n.s. 4], S, 13-39 (1941). 



927 W. M. Sperry and B. Schick, Am. J. Diseases Children, 51, 1372-1384 (1936). 



