Soft tissue: well-differentiated liposarcoma: 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 · Soft tissue: well-differentiated liposarcoma

Sample item

A 60-year-old man has a 25 cm retroperitoneal fatty mass. Histology shows mature adipocytes of varying size with atypical hyperchromatic stromal cells and occasional lipoblasts. Which genetic alteration is expected in this well-differentiated tumour?

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

The answer and the reasoning

A. MDM2 amplification on chromosome 12q13-15

Well-differentiated and dedifferentiated liposarcomas carry ring or giant marker chromosomes amplifying 12q13-15, which includes MDM2 and CDK4. MDM2 degrades p53, so its amplification removes p53 function. MDM2 immunostaining or FISH helps to distinguish the tumour from a benign lipoma.

Option by option

  • A. MDM2 amplification on chromosome 12q13-15 (correct)

    Correct. MDM2 amplification characterises these liposarcomas.

  • B. t(X;18) producing SS18-SSX fusion

    SS18-SSX arises from t(X;18) in synovial sarcoma.

  • C. t(11;22) producing EWSR1-FLI1 fusion

    EWSR1-FLI1 from t(11;22) characterises Ewing sarcoma.

  • D. t(2;13) producing PAX3-FOXO1 fusion

    PAX3-FOXO1 from t(2;13) characterises alveolar rhabdomyosarcoma.

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 A, MDM2 amplification on chromosome 12q13-15. Well-differentiated and dedifferentiated liposarcomas carry ring or giant marker chromosomes amplifying 12q13-15, which includes MDM2 and CDK4.

Why is "t(X;18) producing SS18-SSX fusion" not the answer?

SS18-SSX arises from t(X;18) in synovial sarcoma.

Why is "t(11;22) producing EWSR1-FLI1 fusion" not the answer?

EWSR1-FLI1 from t(11;22) characterises Ewing sarcoma.

Why is "t(2;13) producing PAX3-FOXO1 fusion" not the answer?

PAX3-FOXO1 from t(2;13) characterises alveolar rhabdomyosarcoma.

What concept does this question test?

It tests Soft tissue: well-differentiated liposarcoma in Pathology. MDM2 degrades p53, so its amplification removes p53 function. MDM2 immunostaining or FISH helps to distinguish the tumour from a benign lipoma.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Soft tissue: well-differentiated liposarcoma?

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.