This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Malnutrition, Subject name: Pediatrics
Casal necklace is seen in? 
Select and explain. 
A. Scurvy, B. Kwashiorkar, C. Pellagra, D. Indicanuria
C: Pellagra
Answer: C: Pellagra 
Explanation: Casal necklace is seen in: Pellagra Due to deficiency of Niacin / Vitamin B3. Tryptophan is used to produce niacin. Niacin deficiency occurs in hanup disease (defect in the transpoation of neutral amino acids) , maize-based diets and carcinoid syndrome. Characterised by 3Ds- Diarrhea, Dermatitis (Casal necklace), Dementia, and finally death.