Systemic pathology: aneurysmal bone cyst: 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 · Systemic pathology: aneurysmal bone cyst

Sample item

A 12-year-old girl has pain and swelling over the proximal tibia. Radiograph shows an eccentric, expansile lytic lesion with a thin shell, and MRI shows multiple fluid-fluid levels. Histology shows blood-filled spaces separated by fibrous septa containing bland spindle cells and giant cells, with no atypia or malignant osteoid. What is the diagnosis?

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

The answer and the reasoning

D. Aneurysmal bone cyst

Aneurysmal bone cyst consists of blood-filled spaces without an endothelial lining, separated by septa with bland cells and giant cells, and many carry USP6 rearrangements. The absence of atypia and tumour osteoid separates it from telangiectatic osteosarcoma.

Option by option

  • A. Telangiectatic osteosarcoma

    Telangiectatic osteosarcoma shows high-grade atypical cells and malignant osteoid, which are absent here.

  • B. Simple (unicameral) bone cyst

    A simple bone cyst is a single fluid-filled cavity in the metaphysis, not a multiloculated blood-filled lesion.

  • C. Giant cell tumour of bone

    Giant cell tumour occurs at the epiphysis of mature bones and is composed of sheets of mononuclear cells with giant cells.

  • D. Aneurysmal bone cyst (correct)

    Correct. Blood-filled spaces with bland septa and fluid levels indicate an aneurysmal bone 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 Pathology question

What is the answer to this Pathology question?

The best answer is D, Aneurysmal bone cyst. Aneurysmal bone cyst consists of blood-filled spaces without an endothelial lining, separated by septa with bland cells and giant cells, and many carry USP6 rearrangements.

Why is "Telangiectatic osteosarcoma" not the answer?

Telangiectatic osteosarcoma shows high-grade atypical cells and malignant osteoid, which are absent here.

Why is "Simple (unicameral) bone cyst" not the answer?

A simple bone cyst is a single fluid-filled cavity in the metaphysis, not a multiloculated blood-filled lesion.

Why is "Giant cell tumour of bone" not the answer?

Giant cell tumour occurs at the epiphysis of mature bones and is composed of sheets of mononuclear cells with giant cells.

What concept does this question test?

It tests Systemic pathology: aneurysmal bone cyst in Pathology. The absence of atypia and tumour osteoid separates it from telangiectatic osteosarcoma.

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 Systemic pathology: aneurysmal bone cyst?

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.