Pigmentary disorders: exogenous ochronosis: 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: exogenous ochronosis

Sample item

A woman applied 4 percent hydroquinone to melasma continuously for several years. She now has blue-black sooty macules and papules over the cheeks. Alkaptonuria is excluded. What is the diagnosis?

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

The answer and the reasoning

D. Exogenous ochronosis

Prolonged use of high-concentration hydroquinone, especially in dark skin and with sun exposure, can cause exogenous ochronosis: blue-black or grey-brown pigment with a caviar-like papular texture. Biopsy shows banana-shaped ochre fibres in the dermis. It is difficult to treat and stopping the agent is the first step.

Option by option

  • A. Nevus of Ota

    Nevus of Ota is a congenital or early dermal melanocytosis in the trigeminal territory, usually unilateral.

  • B. Post-inflammatory hyperpigmentation

    Post-inflammatory hyperpigmentation is brown and follows inflammation, without a blue-black sooty papular texture.

  • C. Riehl melanosis

    Riehl melanosis is a pigmented contact dermatitis from fragrances or dyes, not related to hydroquinone.

  • D. Exogenous ochronosis (correct)

    Correct. Long-term hydroquinone deposits ochronotic pigment in the dermis, giving blue-black sooty lesions.

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 D, Exogenous ochronosis. Prolonged use of high-concentration hydroquinone, especially in dark skin and with sun exposure, can cause exogenous ochronosis: blue-black or grey-brown pigment with a caviar-like papular texture.

Why is "Nevus of Ota" not the answer?

Nevus of Ota is a congenital or early dermal melanocytosis in the trigeminal territory, usually unilateral.

Why is "Post-inflammatory hyperpigmentation" not the answer?

Post-inflammatory hyperpigmentation is brown and follows inflammation, without a blue-black sooty papular texture.

Why is "Riehl melanosis" not the answer?

Riehl melanosis is a pigmented contact dermatitis from fragrances or dyes, not related to hydroquinone.

What concept does this question test?

It tests Pigmentary disorders: exogenous ochronosis in Dermatology. Biopsy shows banana-shaped ochre fibres in the dermis. It is difficult to treat and stopping the agent is the first step.

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: exogenous ochronosis?

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.