Skin tumours: dermatofibrosarcoma protuberans: practice question

A Dermatology 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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Dermatology · Skin tumours: dermatofibrosarcoma protuberans

Sample item

A young adult has a slowly growing, indurated plaque on the trunk that recurs after simple excision. Biopsy shows spindle cells in a storiform pattern infiltrating fat in a honeycomb pattern. Which translocation is typical?

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

The answer and the reasoning

A. t(17;22) COL1A1-PDGFB

Dermatofibrosarcoma protuberans harbours a COL1A1-PDGFB fusion, driving PDGF signalling, and responds to imatinib when inoperable. It is locally aggressive and best treated with wide excision or Mohs surgery.

Option by option

  • A. t(17;22) COL1A1-PDGFB (correct)

    Correct. COL1A1-PDGFB fusion defines DFSP.

  • B. t(X;18) SS18-SSX

    SS18-SSX characterises synovial sarcoma.

  • C. t(11;22) EWS-FLI1

    EWS-FLI1 is found in Ewing sarcoma.

  • D. t(9;22) BCR-ABL

    BCR-ABL is the Philadelphia chromosome in CML.

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.

More Dermatology questions

Questions about this Dermatology question

What is the answer to this Dermatology question?

The best answer is A, t(17;22) COL1A1-PDGFB. Dermatofibrosarcoma protuberans harbours a COL1A1-PDGFB fusion, driving PDGF signalling, and responds to imatinib when inoperable.

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

SS18-SSX characterises synovial sarcoma.

Why is "t(11;22) EWS-FLI1" not the answer?

EWS-FLI1 is found in Ewing sarcoma.

Why is "t(9;22) BCR-ABL" not the answer?

BCR-ABL is the Philadelphia chromosome in CML.

What concept does this question test?

It tests Skin tumours: dermatofibrosarcoma protuberans in Dermatology. It is locally aggressive and best treated with wide excision or Mohs surgery.

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 Skin tumours: dermatofibrosarcoma protuberans?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.