Systemic pathology: undifferentiated pleomorphic sarcoma: 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: undifferentiated pleomorphic sarcoma

Sample item

A 62-year-old man has a deep thigh mass. Histology shows storiform spindle cells and bizarre multinucleated giant cells. Immunostains for desmin, S100, cytokeratin and CD34 are negative. What is the diagnosis?

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

The answer and the reasoning

C. Undifferentiated pleomorphic sarcoma

Undifferentiated pleomorphic sarcoma is a high-grade sarcoma of adults that shows no specific line of differentiation, and it is a diagnosis of exclusion after immunohistochemistry. Many tumours formerly called malignant fibrous histiocytoma are reclassified into specific types.

Option by option

  • A. Dedifferentiated liposarcoma

    Dedifferentiated liposarcoma contains a well-differentiated fatty component and MDM2 amplification.

  • B. Leiomyosarcoma

    Leiomyosarcoma shows smooth muscle differentiation and is positive for desmin and smooth muscle actin.

  • C. Undifferentiated pleomorphic sarcoma (correct)

    Correct. High-grade pleomorphic sarcoma with no lineage markers fits an undifferentiated pleomorphic sarcoma.

  • D. Dermatofibrosarcoma protuberans

    Dermatofibrosarcoma protuberans is a superficial CD34 positive tumour of the skin.

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 C, Undifferentiated pleomorphic sarcoma. Undifferentiated pleomorphic sarcoma is a high-grade sarcoma of adults that shows no specific line of differentiation, and it is a diagnosis of exclusion after immunohistochemistry.

Why is "Dedifferentiated liposarcoma" not the answer?

Dedifferentiated liposarcoma contains a well-differentiated fatty component and MDM2 amplification.

Why is "Leiomyosarcoma" not the answer?

Leiomyosarcoma shows smooth muscle differentiation and is positive for desmin and smooth muscle actin.

Why is "Dermatofibrosarcoma protuberans" not the answer?

Dermatofibrosarcoma protuberans is a superficial CD34 positive tumour of the skin.

What concept does this question test?

It tests Systemic pathology: undifferentiated pleomorphic sarcoma in Pathology. Many tumours formerly called malignant fibrous histiocytoma are reclassified into specific types.

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 Systemic pathology: undifferentiated pleomorphic sarcoma?

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.