Pigmentary disorders: cobalamin deficiency: 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 · Pigmentary disorders: cobalamin deficiency

Sample item

A strict vegetarian has fatigue, sore red tongue and bluish-brown hyperpigmentation of the knuckles and palmar creases. Blood film shows macrocytosis and hypersegmented neutrophils. Which deficiency is most likely?

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

The answer and the reasoning

C. Vitamin B12

Vitamin B12 deficiency can cause reversible hyperpigmentation, typically of the knuckles, palms, soles and mucosae, with glossitis and megaloblastic anaemia. It is more evident in dark skin and resolves with replacement. A strict vegetarian diet is a common cause in India.

Option by option

  • A. Vitamin A

    Vitamin A deficiency causes follicular hyperkeratosis and night blindness.

  • B. Niacin

    Niacin deficiency causes pellagra, with photosensitive dermatitis, diarrhoea and dementia, not macrocytosis.

  • C. Vitamin B12 (correct)

    Correct. B12 deficiency gives macrocytic anaemia, glossitis and knuckle hyperpigmentation.

  • D. Ascorbic acid

    Ascorbic acid deficiency causes scurvy, with perifollicular haemorrhages and bleeding gums.

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 C, Vitamin B12. Vitamin B12 deficiency can cause reversible hyperpigmentation, typically of the knuckles, palms, soles and mucosae, with glossitis and megaloblastic anaemia.

Why is "Vitamin A" not the answer?

Vitamin A deficiency causes follicular hyperkeratosis and night blindness.

Why is "Niacin" not the answer?

Niacin deficiency causes pellagra, with photosensitive dermatitis, diarrhoea and dementia, not macrocytosis.

Why is "Ascorbic acid" not the answer?

Ascorbic acid deficiency causes scurvy, with perifollicular haemorrhages and bleeding gums.

What concept does this question test?

It tests Pigmentary disorders: cobalamin deficiency in Dermatology. It is more evident in dark skin and resolves with replacement. A strict vegetarian diet is a common cause in India.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Pigmentary disorders: cobalamin deficiency?

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.