Neoplasia: immunohistochemistry of undifferentiated tumours: 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 · Neoplasia: immunohistochemistry of undifferentiated tumours

Sample item

A 55-year-old man has an axillary lymph node replaced by large pleomorphic cells with prominent nucleoli. Cytokeratin, LCA and desmin are negative. Which set of markers would best confirm melanoma?

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

The answer and the reasoning

A. S-100, HMB-45 and Melan-A

Poorly differentiated metastatic tumours are classified by immunohistochemistry. Cytokeratin marks carcinoma, LCA lymphoma and desmin muscle tumours. Melanoma is typically positive for S-100, SOX10, HMB-45 and Melan-A.

Option by option

  • A. S-100, HMB-45 and Melan-A (correct)

    S-100, HMB-45 and Melan-A identify melanocytic differentiation.

  • B. CD20 and CD3

    CD20 and CD3 identify B and T lymphocytes, and LCA is already negative here.

  • C. Chromogranin and synaptophysin

    Chromogranin and synaptophysin identify neuroendocrine tumours.

  • D. Desmin and myogenin

    Desmin and myogenin identify skeletal muscle differentiation, as in 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.

More Pathology questions

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is A, S-100, HMB-45 and Melan-A. Poorly differentiated metastatic tumours are classified by immunohistochemistry.

Why is "CD20 and CD3" not the answer?

CD20 and CD3 identify B and T lymphocytes, and LCA is already negative here.

Why is "Chromogranin and synaptophysin" not the answer?

Chromogranin and synaptophysin identify neuroendocrine tumours.

Why is "Desmin and myogenin" not the answer?

Desmin and myogenin identify skeletal muscle differentiation, as in rhabdomyosarcoma.

What concept does this question test?

It tests Neoplasia: immunohistochemistry of undifferentiated tumours in Pathology. Cytokeratin marks carcinoma, LCA lymphoma and desmin muscle tumours. Melanoma is typically positive for S-100, SOX10, HMB-45 and Melan-A.

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 Neoplasia: immunohistochemistry of undifferentiated tumours?

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.