Respiratory: hypersensitivity pneumonitis: 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 · Respiratory: hypersensitivity pneumonitis

Sample item

A 45-year-old farmer develops fever, cough and dyspnoea about 6 hours after handling mouldy hay, which settles in a few days and recurs on re-exposure. Biopsy shows lymphocytic interstitial infiltrate and poorly formed non-necrotising granulomas. Which mechanism is responsible?

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

The answer and the reasoning

D. Type III and type IV hypersensitivity to inhaled antigens of thermophilic actinomycetes

Farmer lung is a form of extrinsic allergic alveolitis. Repeated exposure to antigens of thermophilic actinomycetes produces immune complex (type III) injury in the acute phase and T-cell mediated (type IV) granulomatous inflammation in subacute and chronic disease. Avoiding the antigen is the key treatment.

Option by option

  • A. Type II antibodies against the alveolar basement membrane

    Anti-basement membrane antibodies cause Goodpasture disease with alveolar haemorrhage.

  • B. Direct fibrogenic injury from inhaled free silica

    Silica causes silicotic nodules and fibrosis over years, not recurrent febrile episodes after exposure.

  • C. Type I IgE-mediated mast cell degranulation in the bronchi

    IgE-mediated disease causes immediate bronchospasm within minutes and no granulomas.

  • D. Type III and type IV hypersensitivity to inhaled antigens of thermophilic actinomycetes (correct)

    Correct. Type III and type IV reactions explain the delayed onset and the 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 Pathology question

What is the answer to this Pathology question?

The best answer is D, Type III and type IV hypersensitivity to inhaled antigens of thermophilic actinomycetes. Farmer lung is a form of extrinsic allergic alveolitis.

Why is "Type II antibodies against the alveolar basement membrane" not the answer?

Anti-basement membrane antibodies cause Goodpasture disease with alveolar haemorrhage.

Why is "Direct fibrogenic injury from inhaled free silica" not the answer?

Silica causes silicotic nodules and fibrosis over years, not recurrent febrile episodes after exposure.

Why is "Type I IgE-mediated mast cell degranulation in the bronchi" not the answer?

IgE-mediated disease causes immediate bronchospasm within minutes and no granulomas.

What concept does this question test?

It tests Respiratory: hypersensitivity pneumonitis in Pathology. Repeated exposure to antigens of thermophilic actinomycetes produces immune complex (type III) injury in the acute phase and T-cell mediated (type IV) granulomatous inflammation in subacute and chronic disease. Avoiding the antigen is the key 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 Respiratory: hypersensitivity pneumonitis?

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.