Systemic pathology: pulmonary alveolar proteinosis: 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 · Systemic pathology: pulmonary alveolar proteinosis

Sample item

A 35-year-old smoker has progressive dyspnoea. Bronchoalveolar lavage returns milky fluid. Biopsy shows alveoli filled with granular, PAS-positive eosinophilic material while the alveolar walls are preserved. What is the underlying mechanism?

AType III hypersensitivity to inhaled organic dustsBDeficiency of alpha-1 antitrypsinCExcess surfactant secretion from hyperplastic bronchial glandsDAutoantibodies to GM-CSF impairing macrophage surfactant clearance

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

The answer and the reasoning

D. Autoantibodies to GM-CSF impairing macrophage surfactant clearance

Autoimmune pulmonary alveolar proteinosis is caused by autoantibodies to GM-CSF, which prevent alveolar macrophages from clearing surfactant. Lipoproteinaceous material fills the alveoli without destroying the architecture, and whole lung lavage relieves symptoms.

Option by option

A. Type III hypersensitivity to inhaled organic dusts
Type III hypersensitivity to organic dusts causes hypersensitivity pneumonitis with granulomas and interstitial inflammation.
B. Deficiency of alpha-1 antitrypsin
Alpha-1 antitrypsin deficiency causes panacinar emphysema, not alveolar filling.
C. Excess surfactant secretion from hyperplastic bronchial glands
Bronchial glands do not produce surfactant, which is made by type II pneumocytes.
D. Autoantibodies to GM-CSF impairing macrophage surfactant clearance (correct)
Correct. GM-CSF blockade stops macrophages from clearing surfactant, so it accumulates in the alveoli.

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 D, Autoantibodies to GM-CSF impairing macrophage surfactant clearance. Autoimmune pulmonary alveolar proteinosis is caused by autoantibodies to GM-CSF, which prevent alveolar macrophages from clearing surfactant.

Why is "Type III hypersensitivity to inhaled organic dusts" not the answer?

Type III hypersensitivity to organic dusts causes hypersensitivity pneumonitis with granulomas and interstitial inflammation.

Why is "Deficiency of alpha-1 antitrypsin" not the answer?

Alpha-1 antitrypsin deficiency causes panacinar emphysema, not alveolar filling.

Why is "Excess surfactant secretion from hyperplastic bronchial glands" not the answer?

Bronchial glands do not produce surfactant, which is made by type II pneumocytes.

What concept does this question test?

It tests Systemic pathology: pulmonary alveolar proteinosis in Pathology. Lipoproteinaceous material fills the alveoli without destroying the architecture, and whole lung lavage relieves symptoms.

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: pulmonary alveolar proteinosis?

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.