Haematology: acute myeloid leukaemia cytochemistry: 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: acute myeloid leukaemia cytochemistry

Sample item

A peripheral smear from a 50-year-old man shows 60% blasts, some containing needle-shaped cytoplasmic rods. Which cytochemical or immunophenotypic pattern is expected in these blasts?

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

The answer and the reasoning

B. Myeloperoxidase positive and TdT negative

Auer rods are condensed azurophilic granules and are pathognomonic of myeloid differentiation. Myeloblasts stain for myeloperoxidase and Sudan black and lack TdT, whereas lymphoblasts are MPO negative, TdT positive and often PAS block positive. TRAP positivity marks hairy cell leukaemia.

Option by option

  • A. Strong tartrate-resistant acid phosphatase positivity

    TRAP is a marker of hairy cell leukaemia, not of blasts with Auer rods.

  • B. Myeloperoxidase positive and TdT negative (correct)

    Auer rods mark myeloid blasts, which are MPO positive and TdT negative.

  • C. Myeloperoxidase negative, TdT positive and PAS block positive

    MPO-negative, TdT-positive, PAS-positive blasts are lymphoblasts of ALL.

  • D. Low leucocyte alkaline phosphatase score with basophilia

    Low leucocyte alkaline phosphatase with basophilia describes chronic myeloid leukaemia.

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 B, Myeloperoxidase positive and TdT negative. Auer rods are condensed azurophilic granules and are pathognomonic of myeloid differentiation.

Why is "Strong tartrate-resistant acid phosphatase positivity" not the answer?

TRAP is a marker of hairy cell leukaemia, not of blasts with Auer rods.

Why is "Myeloperoxidase negative, TdT positive and PAS block positive" not the answer?

MPO-negative, TdT-positive, PAS-positive blasts are lymphoblasts of ALL.

Why is "Low leucocyte alkaline phosphatase score with basophilia" not the answer?

Low leucocyte alkaline phosphatase with basophilia describes chronic myeloid leukaemia.

What concept does this question test?

It tests Haematology: acute myeloid leukaemia cytochemistry in Pathology. Myeloblasts stain for myeloperoxidase and Sudan black and lack TdT, whereas lymphoblasts are MPO negative, TdT positive and often PAS block positive. TRAP positivity marks hairy cell leukaemia.

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: acute myeloid leukaemia cytochemistry?

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.