Musculoskeletal imaging: congenital pseudarthrosis of the tibia: practice question

A Radiology 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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Radiology · Musculoskeletal imaging: congenital pseudarthrosis of the tibia

Sample item

A 2-year-old with multiple café-au-lait macules and axillary freckling has anterolateral bowing of the tibia. Radiographs show narrowing and sclerosis of the mid-tibia with a fracture that has not united. What is the diagnosis?

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

The answer and the reasoning

A. Congenital pseudarthrosis of the tibia

Anterolateral tibial bowing with a narrowed, sclerotic segment that fractures and fails to unite is congenital pseudarthrosis, and about half of cases are associated with neurofibromatosis type 1. Medial bowing with a beaked medial metaphysis is Blount disease instead.

Option by option

  • A. Congenital pseudarthrosis of the tibia (correct)

    Correct. Anterolateral bowing, sclerosis and nonunion in a child with neurofibromatosis features indicates congenital pseudarthrosis.

  • B. Infantile tibia vara

    Infantile tibia vara causes medial bowing with a depressed, beaked medial tibial metaphysis.

  • C. Rickets

    Rickets causes metaphyseal widening and cupping with generalised poor mineralisation.

  • D. Fibrous dysplasia

    Fibrous dysplasia gives an expansile ground-glass lesion rather than a narrowed sclerotic segment that fails to unite.

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 Radiology question

What is the answer to this Radiology question?

The best answer is A, Congenital pseudarthrosis of the tibia. Anterolateral tibial bowing with a narrowed, sclerotic segment that fractures and fails to unite is congenital pseudarthrosis, and about half of cases are associated with neurofibromatosis type 1.

Why is "Infantile tibia vara" not the answer?

Infantile tibia vara causes medial bowing with a depressed, beaked medial tibial metaphysis.

Why is "Rickets" not the answer?

Rickets causes metaphyseal widening and cupping with generalised poor mineralisation.

Why is "Fibrous dysplasia" not the answer?

Fibrous dysplasia gives an expansile ground-glass lesion rather than a narrowed sclerotic segment that fails to unite.

What concept does this question test?

It tests Musculoskeletal imaging: congenital pseudarthrosis of the tibia in Radiology. Medial bowing with a beaked medial metaphysis is Blount disease instead.

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 Musculoskeletal imaging: congenital pseudarthrosis of the tibia?

Learn signs with the image, and the disease they point to. Then use the flashcards and the other Radiology 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.