Chest imaging: hydatid: 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 imaging: hydatid

Sample item

A chest radiograph shows a well-defined cystic lesion in the lower zone with a double arc and air between the layers of the wall, which later shows floating collapsed membranes. Which pair of signs is described?

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

The answer and the reasoning

D. Crescent (meniscus) sign and water-lily sign of hydatid cyst

In pulmonary hydatid disease, air tracks between the pericyst and endocyst forming a crescent sign, and with rupture the collapsed endocyst floats on residual fluid like a water lily (Camalote sign). Surgery is the usual treatment with albendazole. Aspiration is avoided because of the risk of anaphylaxis.

Option by option

  • A. Golden S sign and Rigler sign

    Golden S indicates lobar collapse and Rigler sign indicates pneumoperitoneum.

  • B. Hampton hump and Westermark sign

    These are signs of pulmonary embolism.

  • C. Halo sign and reverse halo sign

    These are signs of invasive fungal disease and organising pneumonia.

  • D. Crescent (meniscus) sign and water-lily sign of hydatid cyst (correct)

    Correct. Crescent and water-lily signs describe hydatid cyst.

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 D, Crescent (meniscus) sign and water-lily sign of hydatid cyst. In pulmonary hydatid disease, air tracks between the pericyst and endocyst forming a crescent sign, and with rupture the collapsed endocyst floats on residual fluid like a water lily (Camalote sign).

Why is "Golden S sign and Rigler sign" not the answer?

Golden S indicates lobar collapse and Rigler sign indicates pneumoperitoneum.

Why is "Hampton hump and Westermark sign" not the answer?

These are signs of pulmonary embolism.

Why is "Halo sign and reverse halo sign" not the answer?

These are signs of invasive fungal disease and organising pneumonia.

What concept does this question test?

It tests Chest imaging: hydatid in Radiology. Surgery is the usual treatment with albendazole. Aspiration is avoided because of the risk of anaphylaxis.

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 imaging: hydatid?

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.