Musculoskeletal imaging: bone scan in myeloma: 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 · Musculoskeletal imaging: bone scan in myeloma

Sample item

A 62-year-old has bone pain and anaemia, and a skeletal survey shows multiple lytic lesions. A Tc-99m MDP bone scan is nearly normal. What is the best explanation?

AThe tracer binds only to cortical boneBThe lesions are purely lytic with little osteoblastic reactionCMarrow involvement blocks renal tracer excretionDPlasma cells rapidly clear the tracer

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

The answer and the reasoning

B. The lesions are purely lytic with little osteoblastic reaction

Tc-99m MDP uptake depends on osteoblastic activity and blood flow. Myeloma lesions are osteoclastic with minimal new bone formation, so they can be cold or normal, and a skeletal survey, MRI or PET is preferred.

Option by option

A. The tracer binds only to cortical bone
The tracer binds to hydroxyapatite in both cortical and trabecular bone, so this does not explain the findings.
B. The lesions are purely lytic with little osteoblastic reaction (correct)
Correct. Uptake reflects bone formation, which is minimal in purely lytic myeloma lesions.
C. Marrow involvement blocks renal tracer excretion
Renal excretion of the tracer is not blocked by marrow involvement.
D. Plasma cells rapidly clear the tracer
Plasma cells do not clear the tracer; the problem is the lack of osteoblastic reaction.

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.

Questions about this Radiology question

What is the answer to this Radiology question?

The best answer is B, The lesions are purely lytic with little osteoblastic reaction. Tc-99m MDP uptake depends on osteoblastic activity and blood flow.

Why is "The tracer binds only to cortical bone" not the answer?

The tracer binds to hydroxyapatite in both cortical and trabecular bone, so this does not explain the findings.

Why is "Marrow involvement blocks renal tracer excretion" not the answer?

Renal excretion of the tracer is not blocked by marrow involvement.

Why is "Plasma cells rapidly clear the tracer" not the answer?

Plasma cells do not clear the tracer; the problem is the lack of osteoblastic reaction.

What concept does this question test?

It tests Musculoskeletal imaging: bone scan in myeloma in Radiology. Myeloma lesions are osteoclastic with minimal new bone formation, so they can be cold or normal, and a skeletal survey, MRI or PET is preferred.

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 Musculoskeletal imaging: bone scan in myeloma?

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.