Pellagra — DTM&H MCQ

Correct answer: E — Nicotinamide with nutritional rehabilitation

The correct answer is E, nicotinamide with nutritional rehabilitation. The stem describes classic pellagra: a maize-dominant diet (poor in niacin and tryptophan, especially when the grain is not alkali-treated), a photosensitive hyperpigmented dermatitis affecting sun-exposed skin such as the neck (Casal's necklace), chronic diarrhoea and confusion, the classic triad of dermatitis, diarrhoea and dementia. Maize is low in bioavailable niacin and in tryptophan, so diets dominated by untreated maize (without nixtamalisation/alkali processing) precipitate niacin deficiency. Current guidance recommends oral nicotinamide supplementation together with correction of the underlying dietary deficiency and treatment of any concurrent malnutrition to achieve full recovery. Why the other options are wrong: B. Vitamin C with dental extraction: this describes scurvy management (gum disease, bleeding, poor wound healing from collagen defects), not the pellagra triad described here; there is no mention of gingival bleeding or perifollicular haemorrhage. D. Thiamine before glucose: this is the approach for suspected Wernicke's encephalopathy or beriberi, relevant to thiamine deficiency (confusion plus ophthalmoplegia/ataxia or cardiac failure), but does not explain the photosensitive dermatitis, which is specific to niacin deficiency. C. Vitamin A with measles vaccine: this addresses vitamin A deficiency (xerophthalmia, increased measles mortality), which causes night blindness and corneal changes, not a photosensitive rash or diarrhoea. A. Iron with albendazole: this treats iron deficiency anaemia with concurrent helminth infection, not the described mucocutaneous and neuropsychiatric features of pellagra. Key point: photosensitive dermatitis plus diarrhoea plus dementia in a maize-dependent diet is pellagra from niacin deficiency, treated with nicotinamide and dietary rehabilitation.

Reference: DermNet NZ, Pellagra (vitamin B3/niacin deficiency), citing WHO recommendation of oral nicotinamide for treatment: https://dermnetnz.org/topics/pellagra