Pellagra

A way to think of pellagra from a dermatologic diagnosis standpoint is to think of it as a photosensitive disease that ends up with scaling, skin thickening and erythema, much like lupus, except only more dramatic.  So, you can see the Casal's Necklace, you can see the Gauntlet of scale, and of course you can see the 4 D's of pellagra, Dermatitis, Diarrhea, Dementia and, if allowed to run its course, Death.  What is one source of Niacin in the diet?  One point.

In this moulage, we see thickening of the skin (just like in Casal's Necklace) in a photodistribution.  Since the skin of the hands is constantly being stretched and flexed, we see the fissuring.  Back in the 1800's when the moulage was made, this was not an altogether unusual presentation, and the astute dermatologist would pounce on a case like this, knowing the answer from across the room.  The dermatologists of old were brilliant diagnosticians, just like you, my astute PAs...