Chronic inflammation: spectrum of leprosy: practice question

A Pathology 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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Pathology · Chronic inflammation: spectrum of leprosy

Sample item

A 30-year-old man has a single anaesthetic, hypopigmented, sharply demarcated plaque. A skin biopsy shows well-formed epithelioid granulomas with Langhans giant cells that erode a dermal nerve, and acid-fast bacilli are very scanty on Fite staining. Which immunological state best explains this histology?

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

The answer and the reasoning

C. A strong Th1 response with interferon-gamma activating macrophages

In tuberculoid leprosy a vigorous Th1 response, with interferon-gamma and IL-12, activates macrophages to form epithelioid granulomas that contain the bacilli, so few organisms are seen but nerve damage is marked. In lepromatous leprosy a Th2 pattern gives foamy, bacilli-laden macrophages without granulomas. The tuberculoid pattern is therefore the high-resistance, paucibacillary pole of the spectrum.

Option by option

  • A. Deposition of immune complexes producing a neutrophilic vasculitis

    Immune complex vasculitis underlies erythema nodosum leprosum, a reaction in lepromatous disease, not this stable plaque.

  • B. Complete loss of all T-cell reactivity to every antigen

    The anergy of lepromatous disease is specific to Mycobacterium leprae, and tuberculoid disease has a strong response, not global loss.

  • C. A strong Th1 response with interferon-gamma activating macrophages (correct)

    A Th1 response produces compact granulomas and few bacilli, which matches the biopsy.

  • D. A dominant Th2 response with IL-4 and IL-10 suppressing macrophage activation

    A Th2 pattern gives sheets of foamy macrophages full of bacilli, the lepromatous pole, which is the opposite picture.

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 Pathology question

What is the answer to this Pathology question?

The best answer is C, A strong Th1 response with interferon-gamma activating macrophages. In tuberculoid leprosy a vigorous Th1 response, with interferon-gamma and IL-12, activates macrophages to form epithelioid granulomas that contain the bacilli, so few organisms are seen but nerve damage is marked.

Why is "Deposition of immune complexes producing a neutrophilic vasculitis" not the answer?

Immune complex vasculitis underlies erythema nodosum leprosum, a reaction in lepromatous disease, not this stable plaque.

Why is "Complete loss of all T-cell reactivity to every antigen" not the answer?

The anergy of lepromatous disease is specific to Mycobacterium leprae, and tuberculoid disease has a strong response, not global loss.

Why is "A dominant Th2 response with IL-4 and IL-10 suppressing macrophage ac…" not the answer?

A Th2 pattern gives sheets of foamy macrophages full of bacilli, the lepromatous pole, which is the opposite picture.

What concept does this question test?

It tests Chronic inflammation: spectrum of leprosy in Pathology. In lepromatous leprosy a Th2 pattern gives foamy, bacilli-laden macrophages without granulomas. The tuberculoid pattern is therefore the high-resistance, paucibacillary pole of the spectrum.

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 Chronic inflammation: spectrum of leprosy?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.