Diagnosis: Pellagra
The clinical picture — an elderly alcoholic man whose diet consists mainly of maize (corn), presenting with chronic diarrhoea, photosensitive, sunburn-like dermatitis on sun-exposed skin, and delirium/dementia — is the classic description of Pellagra, caused by deficiency of Niacin (Vitamin B3).
- Maize-based diet: Maize is low in bioavailable niacin and its tryptophan (a niacin precursor) is poorly absorbed unless the grain is alkali-treated (nixtamalized). Populations subsisting predominantly on maize are classically at risk of pellagra.
- Alcoholism: Chronic alcohol use reduces dietary intake, impairs absorption, and interferes with niacin/tryptophan metabolism, making alcoholics a major at-risk group for pellagra in developed settings.
- Clinical features — the "4 D's": Pellagra classically presents with Dermatitis (pigmented, scaly, sunburn-like rash on sun-exposed areas such as the neck "Casal's necklace", hands, and face), Diarrhoea, Dementia/Delirium, and if untreated, Death.
Treatment: Niacin Therapy
The treatment of choice is oral or parenteral Niacin (nicotinamide) replacement, which rapidly reverses the dermatologic, gastrointestinal, and neuropsychiatric manifestations if given before irreversible damage occurs.
Why the Other Options Are Incorrect
- Celiac disease, Gluten free diet: Celiac disease is a gluten-sensitive enteropathy causing malabsorption and diarrhoea, but it does not explain the photosensitive skin lesions or the specific maize-diet/alcoholism risk factors emphasized in this vignette.
- Vitamin B12 deficiency, Parenteral B12 therapy: B12 deficiency causes megaloblastic anaemia and subacute combined degeneration of the cord (sensory ataxia, paraesthesia), not a sunburn-like photosensitive dermatitis; it is also not specifically linked to a maize-predominant diet.
- Whipple's disease, Doxycycline + Trimethoprim: Whipple's disease is a rare bacterial (Tropheryma whipplei) infection causing malabsorption, arthralgia, and diarrhoea, but it is not associated with a maize diet, alcoholism, or photosensitive skin lesions, and is treated with prolonged antibiotics, not niacin.
Therefore, the correct diagnosis is Pellagra, treated with Niacin therapy.
Important Questions from Vitamin B Complex Deficiency
- All of the following cause dementia EXCEPT:
- Which of the following is/are neurological manifestation(s) of vitamin $B_{12}$ deficiency?
1. Poor memory
2. Optic atrophy
3. Personality change
Select the correct answer using the code given below: - Angular stomatitis and cheilosis are indicative of deficiencies of which of the following vitamins?
1. Riboflavin
2. Pyridoxine
3. Thiamine
4. Niacin
Select the correct answer using the code given below: - Confabulation is a feature of the deficiency of:
- All of the following are components of the Wernicke's syndrome EXCEPT:
