Neoplasia: paraneoplastic hypercalcaemia: 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.

Try it

Pathology · Neoplasia: paraneoplastic hypercalcaemia

Sample item

A 64-year-old smoker has a cavitating central lung mass with squamous cell carcinoma on biopsy. Serum calcium is 13.8 mg/dL with a suppressed PTH level and no bone metastases. What is the mechanism of the hypercalcaemia?

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

The answer and the reasoning

C. Tumour secretion of parathyroid hormone-related protein

Squamous cell carcinomas of lung, along with carcinomas of breast, kidney and others, can secrete PTHrP, which acts on PTH receptors to increase bone resorption and renal calcium reabsorption. The parathyroid glands are suppressed by the high calcium, so PTH is low. This is humoral hypercalcaemia of malignancy.

Option by option

  • A. Ectopic secretion of intact parathyroid hormone

    Ectopic secretion of intact PTH is rare and would give a raised, not suppressed, PTH.

  • B. Extensive osteolytic bone metastases

    Osteolytic metastases are excluded by the absence of bone metastases in this patient.

  • C. Tumour secretion of parathyroid hormone-related protein (correct)

    PTHrP mimics PTH action while PTH itself is suppressed.

  • D. Calcitriol production by granulomas

    Granulomatous calcitriol production occurs in sarcoidosis and tuberculosis, not squamous carcinoma.

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.

More Pathology questions

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is C, Tumour secretion of parathyroid hormone-related protein. Squamous cell carcinomas of lung, along with carcinomas of breast, kidney and others, can secrete PTHrP, which acts on PTH receptors to increase bone resorption and renal calcium reabsorption.

Why is "Ectopic secretion of intact parathyroid hormone" not the answer?

Ectopic secretion of intact PTH is rare and would give a raised, not suppressed, PTH.

Why is "Extensive osteolytic bone metastases" not the answer?

Osteolytic metastases are excluded by the absence of bone metastases in this patient.

Why is "Calcitriol production by granulomas" not the answer?

Granulomatous calcitriol production occurs in sarcoidosis and tuberculosis, not squamous carcinoma.

What concept does this question test?

It tests Neoplasia: paraneoplastic hypercalcaemia in Pathology. The parathyroid glands are suppressed by the high calcium, so PTH is low. This is humoral hypercalcaemia of malignancy.

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 Neoplasia: paraneoplastic hypercalcaemia?

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.