Renal imaging: xanthogranulomatous pyelonephritis: 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 · Renal imaging: xanthogranulomatous pyelonephritis

Sample item

A diabetic woman with recurrent proteus infections and a long-standing staghorn calculus has CT showing an enlarged non-functioning kidney with multiple low-density rounded calyces around the stone in a bear paw arrangement. What is the diagnosis?

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

The answer and the reasoning

D. Xanthogranulomatous pyelonephritis

A chronic obstructive infection with foamy lipid-laden macrophages enlarges the kidney and creates low-density lipid-filled cavities around a stone, giving the bear paw sign. Nephrectomy is usually required for the diffuse form.

Option by option

  • A. Simple renal cysts

    Simple cysts do not surround a stone in a pattern.

  • B. Acute pyelonephritis

    Acute pyelonephritis shows striated nephrogram and no staghorn stone.

  • C. Renal cell carcinoma

    RCC is a solid enhancing mass.

  • D. Xanthogranulomatous pyelonephritis (correct)

    Correct. A staghorn calculus with a bear paw pattern in a non-functioning kidney fits XGP.

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, Xanthogranulomatous pyelonephritis. A chronic obstructive infection with foamy lipid-laden macrophages enlarges the kidney and creates low-density lipid-filled cavities around a stone, giving the bear paw sign.

Why is "Simple renal cysts" not the answer?

Simple cysts do not surround a stone in a pattern.

Why is "Acute pyelonephritis" not the answer?

Acute pyelonephritis shows striated nephrogram and no staghorn stone.

Why is "Renal cell carcinoma" not the answer?

RCC is a solid enhancing mass.

What concept does this question test?

It tests Renal imaging: xanthogranulomatous pyelonephritis in Radiology. Nephrectomy is usually required for the diffuse form.

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 Renal imaging: xanthogranulomatous pyelonephritis?

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.