Genetic and metabolic disorders: malignant infantile osteopetrosis: practice question

A Pediatrics 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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Pediatrics · Genetic and metabolic disorders: malignant infantile osteopetrosis

Sample item

A 4-month-old has failure to thrive, pallor, hepatosplenomegaly, nystagmus and poor visual response. Radiographs show uniformly dense bones with a bone-within-bone appearance, and the blood film is leucoerythroblastic. Which treatment can be curative?

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

The answer and the reasoning

C. Haematopoietic stem cell transplantation

Malignant infantile osteopetrosis is due to failed osteoclast function. Dense bone crowds out marrow, causing anaemia and extramedullary haematopoiesis, and narrows cranial foramina causing optic nerve compression. Transplant supplies functioning osteoclast precursors.

Option by option

  • A. Pamidronate infusions

    Pamidronate inhibits osteoclasts further and would worsen bone density.

  • B. Splenectomy

    Splenectomy would not correct marrow failure, which arises from encroachment by dense bone.

  • C. Haematopoietic stem cell transplantation (correct)

    Correct. Transplantation replaces the defective osteoclast lineage and is the only curative option.

  • D. High-dose calcitriol alone

    Calcitriol stimulates osteoclast activity and may help only as an adjunct, but it cannot cure the condition.

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 Pediatrics question

What is the answer to this Pediatrics question?

The best answer is C, Haematopoietic stem cell transplantation. Malignant infantile osteopetrosis is due to failed osteoclast function.

Why is "Pamidronate infusions" not the answer?

Pamidronate inhibits osteoclasts further and would worsen bone density.

Why is "Splenectomy" not the answer?

Splenectomy would not correct marrow failure, which arises from encroachment by dense bone.

Why is "High-dose calcitriol alone" not the answer?

Calcitriol stimulates osteoclast activity and may help only as an adjunct, but it cannot cure the condition.

What concept does this question test?

It tests Genetic and metabolic disorders: malignant infantile osteopetrosis in Pediatrics. Dense bone crowds out marrow, causing anaemia and extramedullary haematopoiesis, and narrows cranial foramina causing optic nerve compression. Transplant supplies functioning osteoclast precursors.

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 Genetic and metabolic disorders: malignant infantile osteopetrosis?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics 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.