Haematology: haemophagocytic lymphohistiocytosis: 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: haemophagocytic lymphohistiocytosis

Sample item

A 3-year-old boy has persistent fever, splenomegaly and cytopenias. Ferritin is markedly raised, triglycerides are high and fibrinogen is low. Marrow shows macrophages engulfing red cells and platelets. What is the underlying pathogenesis?

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

The answer and the reasoning

D. Defective cytotoxic lymphocyte killing with uncontrolled macrophage activation

In haemophagocytic lymphohistiocytosis, impaired perforin-dependent cytotoxicity fails to terminate immune activation, so T cells and macrophages drive a cytokine storm. The result is fever, cytopenias, hyperferritinaemia and haemophagocytosis in marrow or spleen.

Option by option

  • A. Deficiency of ADAMTS13 with platelet microthrombi

    ADAMTS13 deficiency causes thrombotic thrombocytopenic purpura with schistocytes, not marrow haemophagocytosis.

  • B. Complement-mediated lysis of red cells lacking GPI-anchored proteins

    Lack of GPI-anchored proteins causes paroxysmal nocturnal haemoglobinuria, which has a very different presentation.

  • C. Clonal proliferation of Langerhans cells with Birbeck granules

    Langerhans cell histiocytosis shows CD1a positive cells with Birbeck granules, not widespread haemophagocytosis.

  • D. Defective cytotoxic lymphocyte killing with uncontrolled macrophage activation (correct)

    Correct. Failure of cytotoxic cells to switch off the immune response leads to macrophage activation and haemophagocytosis.

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, Defective cytotoxic lymphocyte killing with uncontrolled macrophage activation. In haemophagocytic lymphohistiocytosis, impaired perforin-dependent cytotoxicity fails to terminate immune activation, so T cells and macrophages drive a cytokine storm.

Why is "Deficiency of ADAMTS13 with platelet microthrombi" not the answer?

ADAMTS13 deficiency causes thrombotic thrombocytopenic purpura with schistocytes, not marrow haemophagocytosis.

Why is "Complement-mediated lysis of red cells lacking GPI-anchored proteins" not the answer?

Lack of GPI-anchored proteins causes paroxysmal nocturnal haemoglobinuria, which has a very different presentation.

Why is "Clonal proliferation of Langerhans cells with Birbeck granules" not the answer?

Langerhans cell histiocytosis shows CD1a positive cells with Birbeck granules, not widespread haemophagocytosis.

What concept does this question test?

It tests Haematology: haemophagocytic lymphohistiocytosis in Pathology. The result is fever, cytopenias, hyperferritinaemia and haemophagocytosis in marrow or spleen.

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 Haematology: haemophagocytic lymphohistiocytosis?

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.