DYSTROPHIES 



2233 



tropical countries. It was first observed by Cantlie, who called it 

 * tropical mask,' and was later described by one of us. 



etiology. — This is unknown, but a life in the open air with daily 

 long exposure to a tropical sun is apparently an important pre- 

 disposing cause. All our patients were European planters, or native 

 overseers or coohes. 



Symptoms. — Part of the face or the neck, or occasionally the whole 

 face, neck, and chest, presents a peculiar pigmentation, resembling 

 a black bronzine mask; the pigmented areas slowly but steadily 

 increase. The disease is very chronic and incurable if the patient 

 remains in the tropics. The general health is not impaired. The 

 examination of the various organs is negative. The blood and 

 urine are normal. 



Fig. 874. — Chloasma Symmetricum. 



Diagnosis. — This is easy, even in very dark-skinned natives, the 

 affected parts being completely black, and having a characteristic 

 bronzine hue. 



From ordinary chloasma, which is not rare- — especially among 

 women — the affection is easily distinguished by the bronzine tint. 

 The absence of asthenia, loss of flesh, and diarrhoea, will suffice to 

 distinguish chloasma bronzinum from Addison's disease ; the history 

 and the examination of the blood will differentiate it from malarial 

 pseudo- Addison's disease ; the examination of the urine will dis- 

 tinguish it from diabetes bronzinum. Argyria will be excluded by 

 the history and by the fact that in chloasma bronzinum the mucosae 

 are not affected. In ochronosis the cartilages, hgaments, and fibrous 

 structures become pigmented, and the discoloration is best seen 

 about the knuckles and the tendons of the hands and feet; more- 

 over, the urine often blackens on exposure to the air (alcaptonuria) . 



Prognosis and Treatment. — The disease seems to be incurable, 

 but a long stay in a temperate zone generally improves it. 



