Systemic pathology: stalk effect hyperprolactinaemia: 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 · Systemic pathology: stalk effect hyperprolactinaemia

Sample item

A 50-year-old man has headaches and bitemporal hemianopia. MRI shows a large pituitary macroadenoma compressing the stalk. Serum prolactin is mildly raised, and immunostaining of the resected tumour is negative for prolactin. What explains the raised prolactin?

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

The answer and the reasoning

B. Reduced delivery of hypothalamic dopamine to lactotrophs

Prolactin secretion is under tonic inhibition by dopamine reaching the pituitary through the stalk. Compression of the stalk by a mass reduces dopamine delivery, so prolactin rises modestly, usually much less than with a true prolactinoma.

Option by option

  • A. Increased oestrogen drive on the hypothalamus

    Oestrogen can stimulate lactotrophs but it does not explain this picture in a man with a stalk-compressing mass.

  • B. Reduced delivery of hypothalamic dopamine to lactotrophs (correct)

    Correct. Stalk compression removes dopaminergic inhibition of lactotrophs, so prolactin rises modestly.

  • C. Ectopic prolactin secretion by the tumour

    The tumour is negative for prolactin on immunostaining, so the hormone does not come from the tumour cells.

  • D. Excess TRH from primary hypothyroidism

    Primary hypothyroidism raises TRH and may raise prolactin, but there is no evidence of this here.

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 B, Reduced delivery of hypothalamic dopamine to lactotrophs. Prolactin secretion is under tonic inhibition by dopamine reaching the pituitary through the stalk.

Why is "Increased oestrogen drive on the hypothalamus" not the answer?

Oestrogen can stimulate lactotrophs but it does not explain this picture in a man with a stalk-compressing mass.

Why is "Ectopic prolactin secretion by the tumour" not the answer?

The tumour is negative for prolactin on immunostaining, so the hormone does not come from the tumour cells.

Why is "Excess TRH from primary hypothyroidism" not the answer?

Primary hypothyroidism raises TRH and may raise prolactin, but there is no evidence of this here.

What concept does this question test?

It tests Systemic pathology: stalk effect hyperprolactinaemia in Pathology. Compression of the stalk by a mass reduces dopamine delivery, so prolactin rises modestly, usually much less than with a true prolactinoma.

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 Systemic pathology: stalk effect hyperprolactinaemia?

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.