(BMJ)—A 57-yo woman w/ a restricted diet (lacking fruits and vegetables) and chronic alcohol use of ~8 units daily presented w/ a 4-mo hx of mildly painful rash on both legs and feet. Exam: dry, rough skin w/ small cracks and brownish flakes. A blood test confirmed the dx. What is it?
Eczema
Addison dz
Porphyria cutanea tarda
Pellagra
Actinic reticuloid
You are correct. The pt had a low serum vitamin B3 (niacin) level, confirming the clinical dx of pellagra. Alcohol affects niacin metabolism by inhibiting the conversion of tryptophan to niacin. Pellagra typically affects the neck and/or back of the hands, but in this case, only the legs were affected.

BMJ 2019;365:l1892
By vgreene, 10 June, 2019

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