Head and neck tumours: Lugol iodine staining: practice question

A ENT 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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ENT · Head and neck tumours: Lugol iodine staining

Sample item

During oesophagoscopy for a patient with a previous oropharyngeal cancer, Lugol iodine solution is sprayed on the mucosa. How does dysplastic or malignant squamous epithelium appear?

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

The answer and the reasoning

C. Unstained (pale), because it lacks glycogen

Normal squamous epithelium contains glycogen and stains brown with iodine. Dysplastic and malignant cells have little glycogen, so they remain unstained, and the pale areas are biopsied. Toluidine blue is another vital stain, which is taken up by nuclei in abnormal areas.

Option by option

  • A. Dark brown, because it has increased glycogen

    Normal epithelium, not abnormal, stains brown.

  • B. No change in colour for any epithelium

    Staining differs between normal and abnormal mucosa.

  • C. Unstained (pale), because it lacks glycogen (correct)

    Correct. Glycogen-poor abnormal epithelium does not take up iodine.

  • D. Bright blue

    Blue staining is seen with toluidine blue.

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 ENT question

What is the answer to this ENT question?

The best answer is C, Unstained (pale), because it lacks glycogen. Normal squamous epithelium contains glycogen and stains brown with iodine.

Why is "Dark brown, because it has increased glycogen" not the answer?

Normal epithelium, not abnormal, stains brown.

Why is "No change in colour for any epithelium" not the answer?

Staining differs between normal and abnormal mucosa.

Why is "Bright blue" not the answer?

Blue staining is seen with toluidine blue.

What concept does this question test?

It tests Head and neck tumours: Lugol iodine staining in ENT. Dysplastic and malignant cells have little glycogen, so they remain unstained, and the pale areas are biopsied. Toluidine blue is another vital stain, which is taken up by nuclei in abnormal areas.

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 Head and neck tumours: Lugol iodine staining?

Learn tuning fork results and audiogram patterns by sketching them. Then use the flashcards and the other ENT 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.