Gastrointestinal: gastrointestinal stromal tumour: 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 · Gastrointestinal: gastrointestinal stromal tumour

Sample item

A 55-year-old man has gastrointestinal bleeding. Endoscopic ultrasound shows a submucosal gastric mass. Biopsy shows spindle cells positive for CD117 and DOG1. Which treatment targets the underlying driver abnormality?

ATrastuzumab, an anti-HER2 antibodyBRituximab, an anti-CD20 antibodyCVemurafenib, an inhibitor of mutant BRAFDImatinib, an inhibitor of the mutated KIT tyrosine kinase

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

The answer and the reasoning

D. Imatinib, an inhibitor of the mutated KIT tyrosine kinase

Gastrointestinal stromal tumours arise from interstitial cells of Cajal and mostly carry activating mutations of KIT, or less often PDGFRA. The constitutively active receptor tyrosine kinase drives proliferation, so imatinib is effective in advanced and adjuvant settings. Tumour size and mitotic count predict malignant behaviour.

Option by option

A. Trastuzumab, an anti-HER2 antibody
Trastuzumab targets HER2 in breast and gastric adenocarcinoma, not in stromal tumours.
B. Rituximab, an anti-CD20 antibody
Rituximab targets CD20 on B-cell lymphomas and is irrelevant to KIT-driven stromal tumours.
C. Vemurafenib, an inhibitor of mutant BRAF
Vemurafenib targets BRAF V600E in melanoma and some other cancers, not in typical GIST.
D. Imatinib, an inhibitor of the mutated KIT tyrosine kinase (correct)
Correct. KIT-driven tumours respond to imatinib.

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.

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is D, Imatinib, an inhibitor of the mutated KIT tyrosine kinase. Gastrointestinal stromal tumours arise from interstitial cells of Cajal and mostly carry activating mutations of KIT, or less often PDGFRA.

Why is "Trastuzumab, an anti-HER2 antibody" not the answer?

Trastuzumab targets HER2 in breast and gastric adenocarcinoma, not in stromal tumours.

Why is "Rituximab, an anti-CD20 antibody" not the answer?

Rituximab targets CD20 on B-cell lymphomas and is irrelevant to KIT-driven stromal tumours.

Why is "Vemurafenib, an inhibitor of mutant BRAF" not the answer?

Vemurafenib targets BRAF V600E in melanoma and some other cancers, not in typical GIST.

What concept does this question test?

It tests Gastrointestinal: gastrointestinal stromal tumour in Pathology. The constitutively active receptor tyrosine kinase drives proliferation, so imatinib is effective in advanced and adjuvant settings. Tumour size and mitotic count predict malignant behaviour.

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 Gastrointestinal: gastrointestinal stromal tumour?

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.