2228 



D YSIDROSES AND D YSTROPHIES 



Leucoderma is much more common in tropical countries than in 

 temperate zones. The natives of Ceylon and India|have!a dread of 



developing leucoderma, and 

 look upon it as a loathsome 

 disease. 



etiology and Pathology.— 

 The aetiology is unknown. 

 It is generally considered to 

 be a trophoneurosis. Occa- 

 sionally there is evidence of 

 hereditary influences, several 

 members of the same family 

 being affected. The malady 

 may start without any 

 apparent cause, or in some 

 cases may begin after an 

 injury, after a burn, after 

 too strong a caustication. 

 In fact, the application of 

 strong remedies should be 

 used with care in natives. 

 We have seen leucoderma 

 Fig. 871. — Leucoderma in a Sinhalese patches appearing after the 

 Woman. application of pure formalin. 



Patches of leucoderma may 

 develop also in chronic epiphytic skin diseases, the fungi apparently 

 having a deeply disturbing jeffect on the pigment formation. 



Fig. 872. — Leucoderma of the Hands and Arms. 



Symptomatology. — Leucoderma is characterized by the presence 

 of non-pigment ed areas, white, ivory-like, or pinkish. The patches 

 are roundish or oval, with a smooth surface ; they slowly enlarge 

 and coalesce, giving rise to large, irregularly outlined areas. Occa- 

 sionally almost the whole body becomes affected; more often it is 



