MELANIN 397 



Addison's disease is associated with the deposition of a 

 pigment in the skin that is generally considered to be a melanin, 

 differing from that produced normally in the skin only in 

 quantity and not in origin or composition. 1 No satisfactory 

 explanation of the relation of the adrenal to this pigmentation 

 seems yet to have been made, although it is natural to assume 

 that when the function of the adrenal is destroyed, substances 

 accumulate in the blood that have a stimulating effect on 

 the pigment-forming cells. Abnormal proteid katabolism, with 

 excessive accumulation of the chromogenic constituents of the 

 proteid molecule, has been suggested, as also have alterations 

 in the influence of the sympathetic nervous system upon the 

 chromophore cells, for nerve lesions (e. g. y neurofibroma) are 

 often accompanied by pathological pigmentation of the skin. 2 

 As exact chemical studies of the pigment in Addison's disease 

 have not been made, however, we have no positive proof that 

 it is a melanin, hence any speculation as to the cause of its 

 formation is premature. Carbone 3 claims to have isolated from 

 the urine in Addison's disease a pigment that contains much 

 sulphur, and which he considers similar to or identical with the 

 melanogen of melanuria. v. Kahlden, 4 however, has observed 

 crystals resembling hematoidin in the pigmented tissues. 



Ochronosis is a condition characterized by a black pigmen- 

 tation of the cartilages, first described by Virchow in 1866. 

 In 1904 Osier 5 reported two cases, and found but seven others 

 in the literature to that time. The origin and nature of this 

 pigment remain still undecided. Virchow suspected that the 

 condition was due to a permeation of cartilage by hematin 

 derivatives, but Hansemann, finding a case associated with 

 melanuria, considered that the pigment is probably of meta- 

 bolic origin. Hecker and Wolf studied the urine of a similar 

 case, and concluded that the pigment must be melanin. 

 Albrecht, 6 however, suggested a relation of ochronosis to alkap- 

 tonuria, having found hemogentisic acid in the urine of a case 

 reported by him (see " Alkaptonuria "). Osier's two patients 

 were brothers with alkaptonuria, the evidence of ochronosis con- 

 sisting of discoloration of the cartilages of the ears. Langstein 7 



1 Concerning histogenesis of the pigment see Pforringer, Cent. f. Path.. 

 1900(11),!. 



2 See resume* by Schmidt, Ergeb. der Pathol., 1896 (Bd. 3, Abt. 1), 551. 



3 Giorao R Acad. med. di Torino, 1896. 



4 Virchow's Arch., 1888 (114), 65. 



5 Lancet, 1904 (i), 10 (literature). 



6 Zeit. f. Heilk., Path. Abt., 1902 (23), 366. 

 7 Hofmeister's Beitr., 1903 (4), 145. 



