Immunopathology: neonatal lupus: 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 · Immunopathology: neonatal lupus

Sample item

A newborn is found to have a slow heart rate of 50 per minute and complete heart block, with a transient rash. The mother is well but has anti-Ro antibodies. What is the mechanism of the cardiac lesion?

AT-cell mediated rejection of fetal tissueBTransplacental IgG injuring the fetal conduction systemCDirect viral infection of the fetal myocardiumDDeposition of amyloid in the conduction tissue

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

The answer and the reasoning

B. Transplacental IgG injuring the fetal conduction system

Maternal IgG anti-Ro (SSA) and anti-La (SSB) cross the placenta and are thought to cause inflammation and fibrosis of the fetal atrioventricular node, giving congenital heart block. It is a passively acquired autoimmune disease, and the rash and cytopenias fade as maternal antibody is cleared.

Option by option

A. T-cell mediated rejection of fetal tissue
Fetal rejection by maternal T cells is not the mechanism.
B. Transplacental IgG injuring the fetal conduction system (correct)
Correct. Passively transferred maternal IgG damages the developing conduction system.
C. Direct viral infection of the fetal myocardium
Viral myocarditis would not be linked to maternal anti-Ro antibodies.
D. Deposition of amyloid in the conduction tissue
Amyloid is not a feature of a newborn.

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.

Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is B, Transplacental IgG injuring the fetal conduction system. Maternal IgG anti-Ro (SSA) and anti-La (SSB) cross the placenta and are thought to cause inflammation and fibrosis of the fetal atrioventricular node, giving congenital heart block.

Why is "T-cell mediated rejection of fetal tissue" not the answer?

Fetal rejection by maternal T cells is not the mechanism.

Why is "Direct viral infection of the fetal myocardium" not the answer?

Viral myocarditis would not be linked to maternal anti-Ro antibodies.

Why is "Deposition of amyloid in the conduction tissue" not the answer?

Amyloid is not a feature of a newborn.

What concept does this question test?

It tests Immunopathology: neonatal lupus in Pathology. It is a passively acquired autoimmune disease, and the rash and cytopenias fade as maternal antibody is cleared.

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 Immunopathology: neonatal lupus?

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.