Haematology: systemic mastocytosis: 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 · Haematology: systemic mastocytosis

Sample item

A 45-year-old man has brown macules that urticate when stroked, episodic flushing, abdominal cramps and bone pain. Bone marrow shows aggregates of spindle-shaped mast cells and serum tryptase is raised. Which mutation is characteristic?

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

The answer and the reasoning

D. KIT D816V

Systemic mastocytosis is a clonal mast cell proliferation in which most cases carry the activating KIT D816V mutation. Skin lesions (urticaria pigmentosa) show Darier sign, and mediator release causes flushing and cramps. Raised serum tryptase supports the diagnosis.

Option by option

  • A. JAK2 V617F

    JAK2 V617F occurs in polycythaemia vera, essential thrombocythaemia and primary myelofibrosis.

  • B. FLT3 internal tandem duplication

    FLT3 internal tandem duplication occurs in acute myeloid leukaemia.

  • C. BCR-ABL1 fusion

    BCR-ABL1 defines chronic myeloid leukaemia.

  • D. KIT D816V (correct)

    Correct. Activating KIT D816V drives mast cell proliferation.

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 D, KIT D816V. Systemic mastocytosis is a clonal mast cell proliferation in which most cases carry the activating KIT D816V mutation.

Why is "JAK2 V617F" not the answer?

JAK2 V617F occurs in polycythaemia vera, essential thrombocythaemia and primary myelofibrosis.

Why is "FLT3 internal tandem duplication" not the answer?

FLT3 internal tandem duplication occurs in acute myeloid leukaemia.

Why is "BCR-ABL1 fusion" not the answer?

BCR-ABL1 defines chronic myeloid leukaemia.

What concept does this question test?

It tests Haematology: systemic mastocytosis in Pathology. Skin lesions (urticaria pigmentosa) show Darier sign, and mediator release causes flushing and cramps. Raised serum tryptase supports the diagnosis.

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 Haematology: systemic mastocytosis?

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.