Neoplasia: complete hydatidiform mole: 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 · Neoplasia: complete hydatidiform mole

Sample item

A 24-year-old woman at 11 weeks of amenorrhoea has a uterus of 16 weeks size, serum beta-hCG of 250,000 IU/L and a snowstorm pattern on ultrasound with no fetal parts. Histology shows diffuse hydropic villi with circumferential trophoblastic hyperplasia. What is the expected genetic constitution?

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

The answer and the reasoning

C. 46,XX with all chromosomes of paternal origin

A complete mole arises when an empty ovum is fertilised by a haploid sperm that duplicates, or less often by two sperm, giving a diploid paternal-only genome (usually 46,XX). There is no fetus, and villi are diffusely hydropic with a risk of persistent disease or choriocarcinoma. A partial mole is triploid, usually 69,XXY, and shows focal hydropic change with fetal tissue.

Option by option

  • A. 69,XXY, triploid with two paternal sets

    Triploidy with a fetus or fetal parts defines a partial mole, which this case does not show.

  • B. 45,X with a single maternal set

    Monosomy X with maternal origin is not the genetic basis of hydatidiform mole.

  • C. 46,XX with all chromosomes of paternal origin (correct)

    A purely paternal diploid genome is characteristic of a complete mole.

  • D. 46,XX with one maternal and one paternal set

    Biparental diploid origin is the pattern of a normal conceptus.

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 C, 46,XX with all chromosomes of paternal origin. A complete mole arises when an empty ovum is fertilised by a haploid sperm that duplicates, or less often by two sperm, giving a diploid paternal-only genome (usually 46,XX).

Why is "69,XXY, triploid with two paternal sets" not the answer?

Triploidy with a fetus or fetal parts defines a partial mole, which this case does not show.

Why is "45,X with a single maternal set" not the answer?

Monosomy X with maternal origin is not the genetic basis of hydatidiform mole.

Why is "46,XX with one maternal and one paternal set" not the answer?

Biparental diploid origin is the pattern of a normal conceptus.

What concept does this question test?

It tests Neoplasia: complete hydatidiform mole in Pathology. There is no fetus, and villi are diffusely hydropic with a risk of persistent disease or choriocarcinoma. A partial mole is triploid, usually 69,XXY, and shows focal hydropic change with fetal tissue.

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 Neoplasia: complete hydatidiform mole?

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.