Papulosquamous disorders: pellagra-like dermatitis in Hartnup disease: practice question

A Dermatology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Dermatology · Papulosquamous disorders: pellagra-like dermatitis in Hartnup disease

Sample item

An 8-year-old with an adequate diet has recurrent photosensitive, scaly, pellagra-like dermatitis of the face and hands with episodes of cerebellar ataxia. Urine chromatography shows excess neutral amino acids but normal proline and cystine excretion. What is the most appropriate treatment?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Oral nicotinamide with a high-protein diet

Hartnup disease is an autosomal recessive defect of neutral amino acid transport in the gut and kidney (SLC6A19), leading to tryptophan loss and secondary niacin deficiency. Photosensitive pellagra-like rash and intermittent ataxia respond to nicotinamide, a high-protein diet and sun protection.

Option by option

  • A. Oral nicotinamide with a high-protein diet (correct)

    Correct. Replacing niacin as nicotinamide corrects the pellagra-like features.

  • B. Oral pyridoxine alone

    Pyridoxine treats pyridoxine-dependent states and would not correct tryptophan loss.

  • C. Oral zinc sulphate

    Zinc treats acrodermatitis enteropathica, which has periorificial lesions and diarrhoea in infants.

  • D. Oral biotin

    Biotin treats biotinidase or carboxylase deficiency, which gives a different rash and alopecia.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Dermatology question

What is the answer to this Dermatology question?

The best answer is A, Oral nicotinamide with a high-protein diet. Hartnup disease is an autosomal recessive defect of neutral amino acid transport in the gut and kidney (SLC6A19), leading to tryptophan loss and secondary niacin deficiency.

Why is "Oral pyridoxine alone" not the answer?

Pyridoxine treats pyridoxine-dependent states and would not correct tryptophan loss.

Why is "Oral zinc sulphate" not the answer?

Zinc treats acrodermatitis enteropathica, which has periorificial lesions and diarrhoea in infants.

Why is "Oral biotin" not the answer?

Biotin treats biotinidase or carboxylase deficiency, which gives a different rash and alopecia.

What concept does this question test?

It tests Papulosquamous disorders: pellagra-like dermatitis in Hartnup disease in Dermatology. Photosensitive pellagra-like rash and intermittent ataxia respond to nicotinamide, a high-protein diet and sun protection.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Papulosquamous disorders: pellagra-like dermatitis in Hartnup disease?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.