Leprosy reactions: 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.

Try it

Dermatology · Leprosy reactions

Sample item

A patient with lepromatous leprosy on multidrug therapy develops fever, painful tender erythematous nodules over the limbs, joint pains and neuritis. What is the underlying immunological mechanism?

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

The answer and the reasoning

D. Immune complex deposition (type III hypersensitivity)

Erythema nodosum leprosum is the type 2 lepra reaction, seen mainly in lepromatous and borderline lepromatous disease with a high bacillary load. It is mediated by antigen-antibody complexes and complement, with a systemic illness. Thalidomide and corticosteroids are used for treatment.

Option by option

  • A. Antibody-mediated cytotoxicity (type II hypersensitivity)

    Cytotoxic antibody reactions cause conditions such as haemolysis, not this tender nodular syndrome.

  • B. Delayed-type (type IV) hypersensitivity within existing granulomas

    Delayed-type hypersensitivity underlies the type 1 (reversal) reaction in borderline disease, not erythema nodosum leprosum.

  • C. IgE-mediated (type I) hypersensitivity

    Immediate IgE-mediated hypersensitivity causes urticaria and anaphylaxis, not tender nodules with fever.

  • D. Immune complex deposition (type III hypersensitivity) (correct)

    Correct. Circulating immune complexes with M. leprae antigen deposit in tissues and activate complement.

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.

More Dermatology questions

Questions about this Dermatology question

What is the answer to this Dermatology question?

The best answer is D, Immune complex deposition (type III hypersensitivity). Erythema nodosum leprosum is the type 2 lepra reaction, seen mainly in lepromatous and borderline lepromatous disease with a high bacillary load.

Why is "Antibody-mediated cytotoxicity (type II hypersensitivity)" not the answer?

Cytotoxic antibody reactions cause conditions such as haemolysis, not this tender nodular syndrome.

Why is "Delayed-type (type IV) hypersensitivity within existing granulomas" not the answer?

Delayed-type hypersensitivity underlies the type 1 (reversal) reaction in borderline disease, not erythema nodosum leprosum.

Why is "IgE-mediated (type I) hypersensitivity" not the answer?

Immediate IgE-mediated hypersensitivity causes urticaria and anaphylaxis, not tender nodules with fever.

What concept does this question test?

It tests Leprosy reactions in Dermatology. It is mediated by antigen-antibody complexes and complement, with a systemic illness. Thalidomide and corticosteroids are used for treatment.

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 Leprosy reactions?

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.