I730 



PELLAGRA 



Differential Diagnosis.- — As the symptoms are divisible into 

 three groups, so the discussion of the differential diagnosis is equally 

 capable of arrangement under the same three headings. 



Skin Diseases. — The skin diseases which are to be differentiated 

 from pellagra are classifiable into those resembling the acute 

 cutaneous symptoms and those resembhng the chronic cutaneous 

 appearances. 



1. Resembling the Acute Dermatitis. — Under this heading comes, 

 first of all, erythema solar e, from which pellagra may be distinguished 

 by the inflammation of the mouth, by the presence of the alimentary 

 canal symptoms, and by the vertigo, as well as by the fact that the 

 pellagrous eruption at times appears on parts not usually exposed 

 to the sun, and by the fact that the lesions in sunburn are usually 

 very superficial. 



The same diagnostic points will help to differentiate pellagrous 

 dermatitis from erythema or eczema due to winds, salt air, etc. 



The erythema on the face, hands, arms, etc., in cases of dermatitis 

 venenata may simulate pellagra closely. The pellagrous condition 

 may be differentiated by the presence of gastro-intestinal nervous 

 symptoms, by the less general extension of the eruption, by the less 

 involvement of the eyelids, and by the more acute course. 



From acarine dermatitis pellagra may be distinguished by the 

 localization of the eruption, which does not appear on the trunk, 

 by the absence of the vesiculo- papules and pustules, and hy the 

 absence of itching. 



From alcoholic erythemata it may be recognized by the history 

 of the attack and by the presence of the typical eruption on the 

 hands and feet. 



Some authorities have, however, described, under the term 

 pseudo-pellagra, of alcoholic origin, an erythematous eruption on 

 the hands associated with nervous symptoms which is indistinguish- 

 able from true pellagra, being, in fact, the same disease. 



From angioneurotic oedema it may be differentiated by the absence 

 of marked oedema and the presence of more inflammation in the 

 skin, as well as by the more regular distribution of the eruption, 

 and by the Hmiting line. 



2. Resembling the Chronic Dermatitis.- — From chronic eczema 

 occurring in mentally sound persons or in lunatics pellagra is 

 recognized by the typical distribution of the eruption, by the hne 

 of demarcation, and by the marked pigmentation, when present, 

 and absence of pruritus. From chronic syphilides by the distribu- 

 tion of the eruption, and by the absence of any reaction to mer- 

 cury. Here mention may again be made of the dermotagra on the 

 palms of the hands, over the olecranon, and about the knee, in 

 chronic cases of pellagra, which is apt to be overlooked, or to be 

 considered as points in favour of a diagnosis of eczema rather than 

 of pellagra. 



From biotripsis [vide p. 2282), which it closely resembles, pellagra 

 is differentiated by the limitation of the eruption to the areas so often 



