Pigmentary disorders: Dowling-Degos 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 · Pigmentary disorders: Dowling-Degos disease

Sample item

A woman has had progressive reticulate brown hyperpigmentation of the axillae, groins and neck folds since adolescence, with comedo-like pitted scars on the back. Several relatives are affected. What is the diagnosis?

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

The answer and the reasoning

A. Dowling-Degos disease

Dowling-Degos disease is an autosomal dominant reticulate pigmentary disorder of flexures, from KRT5 or POFUT1 mutations. Histology shows elongated filiform rete ridges with basal hyperpigmentation.

Option by option

  • A. Dowling-Degos disease (correct)

    Correct. Familial flexural reticulate pigmentation with pitted scars is Dowling-Degos disease.

  • B. Acanthosis nigricans

    Acanthosis nigricans shows velvety thickened skin with insulin resistance.

  • C. Dyskeratosis congenita

    Dyskeratosis congenita shows reticulate pigmentation, nail dystrophy and oral leukoplakia.

  • D. Confluent and reticulated papillomatosis

    Confluent and reticulated papillomatosis involves the upper trunk with papillomatous plaques.

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, Dowling-Degos disease. Dowling-Degos disease is an autosomal dominant reticulate pigmentary disorder of flexures, from KRT5 or POFUT1 mutations.

Why is "Acanthosis nigricans" not the answer?

Acanthosis nigricans shows velvety thickened skin with insulin resistance.

Why is "Dyskeratosis congenita" not the answer?

Dyskeratosis congenita shows reticulate pigmentation, nail dystrophy and oral leukoplakia.

Why is "Confluent and reticulated papillomatosis" not the answer?

Confluent and reticulated papillomatosis involves the upper trunk with papillomatous plaques.

What concept does this question test?

It tests Pigmentary disorders: Dowling-Degos disease in Dermatology. Histology shows elongated filiform rete ridges with basal hyperpigmentation.

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 Pigmentary disorders: Dowling-Degos 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.