Leprosy: histology of a reversal reaction: 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 · Leprosy: histology of a reversal reaction

Sample item

A biopsy from an inflamed existing plaque in a patient with borderline leprosy shows epithelioid granulomas with oedema between and within them, swollen epithelioid cells and prominent giant cells. Which process is this?

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

The answer and the reasoning

A. Type 1 (reversal) reaction

A type 1 reaction is a delayed hypersensitivity response, and histology shows dermal and intragranuloma oedema with swollen epithelioid cells and more giant cells. ENL instead shows neutrophils and vasculitis, and Lucio phenomenon shows ischaemic necrosis with endothelial bacilli.

Option by option

  • A. Type 1 (reversal) reaction (correct)

    Correct. Oedema within and between granulomas marks a type 1 reaction.

  • B. Histoid leprosy

    Histoid leprosy shows spindle-shaped histiocytes packed with bacilli forming sharply demarcated nodules.

  • C. Lucio phenomenon

    Lucio phenomenon shows ischaemic epidermal necrosis with bacilli in endothelial cells.

  • D. Erythema nodosum leprosum

    ENL shows a neutrophilic infiltrate with vasculitis in a lepromatous background and not epithelioid granulomas.

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, Type 1 (reversal) reaction. A type 1 reaction is a delayed hypersensitivity response, and histology shows dermal and intragranuloma oedema with swollen epithelioid cells and more giant cells.

Why is "Histoid leprosy" not the answer?

Histoid leprosy shows spindle-shaped histiocytes packed with bacilli forming sharply demarcated nodules.

Why is "Lucio phenomenon" not the answer?

Lucio phenomenon shows ischaemic epidermal necrosis with bacilli in endothelial cells.

Why is "Erythema nodosum leprosum" not the answer?

ENL shows a neutrophilic infiltrate with vasculitis in a lepromatous background and not epithelioid granulomas.

What concept does this question test?

It tests Leprosy: histology of a reversal reaction in Dermatology. ENL instead shows neutrophils and vasculitis, and Lucio phenomenon shows ischaemic necrosis with endothelial bacilli.

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 Leprosy: histology of a reversal reaction?

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.