This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Medicine
"Pellagra" like skin lesion occurs with: 
Select and explain. 
A. Systemic Mastocytosis, B. Bronchial carcinoid, C. Colorectal villous adenoma, D. Medullary thyroid carcinoma
B: Bronchial carcinoid
Answer: B: Bronchial carcinoid 
Explanation: Carcinoid tumors produce the vasoactive substance, Serotonin.A pellagra-like syndrome is probably caused by diversion of large amounts of tryptophan from the synthesis of Vitamin B3 niacin, which is needed for NAD production, to the synthesis of serotonin and other 5-hydroxyindoles(ref:Harper's 27/e p458)