Bone tumours: Langerhans cell histiocytosis: practice question

A Orthopaedics 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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Orthopaedics · Bone tumours: Langerhans cell histiocytosis

Sample item

A 6-year-old has a lytic skull lesion and a single flattened vertebral body (vertebra plana). Biopsy shows cells with Birbeck granules. What is the diagnosis?

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

The answer and the reasoning

D. Langerhans cell histiocytosis (eosinophilic granuloma)

LCH is a clonal proliferation of CD1a-positive, S100-positive Langerhans cells with Birbeck (tennis-racket) granules on electron microscopy. In bone it causes punched-out lytic lesions and vertebra plana, and solitary lesions often resolve with curettage or observation.

Option by option

  • A. Osteomyelitis

    Osteomyelitis causes fever and inflammatory markers.

  • B. Ewing sarcoma

    Ewing sarcoma shows small round blue cells and CD99 positivity.

  • C. Leukaemia

    Leukaemia would show marrow involvement and blood changes.

  • D. Langerhans cell histiocytosis (eosinophilic granuloma) (correct)

    Correct. Vertebra plana and Birbeck granules indicate LCH.

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 Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is D, Langerhans cell histiocytosis (eosinophilic granuloma). LCH is a clonal proliferation of CD1a-positive, S100-positive Langerhans cells with Birbeck (tennis-racket) granules on electron microscopy.

Why is "Osteomyelitis" not the answer?

Osteomyelitis causes fever and inflammatory markers.

Why is "Ewing sarcoma" not the answer?

Ewing sarcoma shows small round blue cells and CD99 positivity.

Why is "Leukaemia" not the answer?

Leukaemia would show marrow involvement and blood changes.

What concept does this question test?

It tests Bone tumours: Langerhans cell histiocytosis in Orthopaedics. In bone it causes punched-out lytic lesions and vertebra plana, and solitary lesions often resolve with curettage or observation.

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 Bone tumours: Langerhans cell histiocytosis?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics 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.