<prompt> Casals necklace is seen in deficiency of: September 2012Vitamin A deficiencyNiacinVitamin B12 deficiencyIron deficiency anemia  <response>: Ans: B i.e. Niacin The Casal collar or Casal necklace is a clinical sign in which there is erythematous pigmented skin rash in the distribution of a broad collar dermatomes C3 and C4. It is seen in patients with pellagra. 