<prompt> Casal necklace is seen in?ScurvyKwashiorkarPellagraIndicanuria  <response>: 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. 