Chest and cardiac imaging: reverse halo sign: practice question

A Radiology 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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Radiology · Chest and cardiac imaging: reverse halo sign

Sample item

A patient with subacute cough and fever has not responded to a course of antibiotics. CT shows a focus of central ground-glass attenuation surrounded by a ring of denser consolidation. Which diagnosis is most likely?

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

The answer and the reasoning

B. Cryptogenic organising pneumonia

A central ground-glass area rimmed by consolidation is the reverse halo, or atoll, sign, most characteristic of organising pneumonia. It also occurs in pulmonary infarcts and some fungal infections.

Option by option

  • A. Pulmonary alveolar proteinosis

    Alveolar proteinosis gives geographic ground glass with septal thickening, the crazy-paving pattern.

  • B. Cryptogenic organising pneumonia (correct)

    Correct. This is a recognised sign of organising pneumonia in a patient unresponsive to antibiotics.

  • C. Usual interstitial pneumonia

    UIP gives basal subpleural reticulation and honeycombing, not a ring of consolidation.

  • D. Hypersensitivity pneumonitis

    Hypersensitivity pneumonitis gives centrilobular nodules, mosaic attenuation and air trapping.

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 Radiology question

What is the answer to this Radiology question?

The best answer is B, Cryptogenic organising pneumonia. A central ground-glass area rimmed by consolidation is the reverse halo, or atoll, sign, most characteristic of organising pneumonia.

Why is "Pulmonary alveolar proteinosis" not the answer?

Alveolar proteinosis gives geographic ground glass with septal thickening, the crazy-paving pattern.

Why is "Usual interstitial pneumonia" not the answer?

UIP gives basal subpleural reticulation and honeycombing, not a ring of consolidation.

Why is "Hypersensitivity pneumonitis" not the answer?

Hypersensitivity pneumonitis gives centrilobular nodules, mosaic attenuation and air trapping.

What concept does this question test?

It tests Chest and cardiac imaging: reverse halo sign in Radiology. It also occurs in pulmonary infarcts and some fungal infections.

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 Chest and cardiac imaging: reverse halo sign?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology 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.