Periodic Acid-Schiff (PAS) Staining MCQs Mock Test (30 MCQs)

Learn PAS staining, a fundamental histochemical technique for detecting glycogen, mucins, and fungal organisms in tissue samples. This comprehensive guide covers:

✓ Chemical Principle:

• Periodic acid oxidation of carbohydrates
• Schiff reagent reaction to produce magenta color

✓ Key Diagnostic Uses:

• Fungal identification (Candida, Aspergillus)
• Renal pathology (basement membrane thickening)
• Glycogen storage diseases
• Adenocarcinomas (mucin detection)

✓ Protocol Variations:

• PAS with diastase digestion (glycogen confirmation)
• Combined PAS-Alcian blue for mucin typing

✓ Interpretation Guide:

• Intensity scoring (0 to 4+)
• Common artifacts and troubleshooting

Essential for histotechnologists, pathologists, and microbiology labs working in anatomic pathology and fungal diagnostics.

Challenge your knowledge with 40+ PAS staining MCQs covering:
◼️ Fungal element identification (hyphae vs. yeast forms)
◼️ Renal biopsy interpretation (diabetic nephropathy)
◼️ Glycogen vs. mucin differentiation
◼️ PAS-D technique applications

Perfect for:

• Pathology board exams (USMLE, FRCPath)
• Histotechnology certification (HT/HTL)
• Medical mycology training

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Hematology Department

Periodic Acid-Schiff (PAS) Staining of Viruses MCQs Mock Test

Challenge your knowledge with 30+ PAS staining MCQs covering:
◼️ Fungal element identification (hyphae vs. yeast forms)
◼️ Renal biopsy interpretation (diabetic nephropathy)
◼️ Glycogen vs. mucin differentiation
◼️ PAS-D technique applications

Perfect for:

• Pathology board exams (USMLE, FRCPath)

• Histotechnology certification (HT/HTL)

• Medical mycology training

Read Full Article: Periodic Acid-Schiff (PAS) Staining 50 FAQ and 30 MCQs

1 / 30

Category: Clinical Laboratory

How do you test the quality of Schiff’s reagent?

Expose to light—should fluoresce

Heat to 60°C—should precipitate

Add to formalin—good reagent turns red-purple immediately

Mix with ethanol—should turn blue

2 / 30

Category: Clinical Laboratory

Which fixative interferes with diastase digestion?

Ethanol

Formalin

Bouin’s (picric acid)

Glutaraldehyde

3 / 30

Category: Clinical Laboratory

PAS staining correlates strongly with which diagnostic technique for autoimmune diseases?

Gram staining

Ziehl-Neelsen stain

Masson’s trichrome

Direct immunofluorescence (DIF)

4 / 30

Category: Clinical Laboratory

PAS-D (diastase) staining helps differentiate:

Glycogen vs. mucin

Collagen vs. reticulin

Amyloid vs. hyaline

Fungi vs. bacteria

5 / 30

Category: Clinical Laboratory

Schiff’s reagent should be stored:

In direct sunlight

At room temperature

In a freezer

Refrigerated (2–8°C)

6 / 30

Category: Clinical Laboratory

Faint PAS staining may result from:

Fresh Schiff’s reagent

Excessive hematoxylin

Short periodic acid exposure

Over-oxidation

7 / 30

Category: Clinical Laboratory

What is the role of Schiff’s reagent in PAS staining?

Digest glycogen

Bind to aldehydes to form a colored product

Counterstain nuclei

Oxidize carbohydrates

8 / 30

Category: Clinical Laboratory

Microwave PAS staining is used for:

Rapid results (e.g., intraoperative)

Eliminating counterstaining

Reducing reagent costs

Enhancing fungal visibility

9 / 30

Category: Clinical Laboratory

PAS staining is contraindicated for:

Frozen sections

None of the above

Tissues fixed in osmium tetroxide

All bacterial infections

10 / 30

Category: Clinical Laboratory

PAS is inferior to mucicarmine for detecting:

Fungal walls

Basement membranes

Glycogen

Epithelial mucins

11 / 30

Category: Clinical Laboratory

Which of the following is NOT PAS-positive?

Collagen (non-reticular)

Mucin

Fungal cell walls

Glycogen

12 / 30

Category: Clinical Laboratory

Expired Schiff’s reagent may cause:

Blue-purple discoloration

Both a and b

Enhanced nuclear staining

Faint staining

13 / 30

Category: Clinical Laboratory

PAS-negative fungi may indicate:

Use of Carnoy’s fixative

Over-fixation

Insufficient periodic acid time

All of the above

14 / 30

Category: Clinical Laboratory

PAS staining is most useful for diagnosing:

Fungal infections

Melanoma

Amyloidosis

Iron overload

15 / 30

Category: Clinical Laboratory

What is used to counterstain nuclei in PAS staining?

Alcian blue

Hematoxylin

Methylene blue

Eosin

16 / 30

Category: Clinical Laboratory

Which stain is MORE sensitive for fungi than PAS?

H&E

Gram stain

Ziehl-Neelsen

Grocott’s methenamine silver (GMS)

17 / 30

Category: Clinical Laboratory

What is the purpose of diastase digestion in PAS staining?

Reduce background staining

Increase mucin visibility

Remove glycogen to confirm its presence

Enhance fungal staining

18 / 30

Category: Clinical Laboratory

Periodic acid is hazardous because it is:

Radioactive

Flammable

Corrosive

Carcinogenic

19 / 30

Category: Clinical Laboratory

Why might glycogen be absent in PAS-stained liver tissue?

Over-oxidation

All of the above

Prolonged formalin fixation

Inadequate diastase digestion

20 / 30

Category: Clinical Laboratory

How long should tissue sections be treated with periodic acid?

5–10 minutes

1 minute

30 minutes

1 hour

21 / 30

Category: Clinical Laboratory

Which chemical group is oxidized by periodic acid in PAS staining?

Carboxyl groups

Phosphate groups

1,2-glycols

Sulfhydryl groups

22 / 30

Category: Clinical Laboratory

If nuclei stain pink instead of blue, what was likely skipped?

Schiff’s reagent

Hematoxylin counterstain

Periodic acid step

Diastase digestion

23 / 30

Category: Clinical Laboratory

Which oxidant is preferred for fungal staining to reduce background?

Periodic acid

Chromic acid

Hydrogen peroxide

Potassium permanganate

24 / 30

Category: Clinical Laboratory

High background staining in PAS can be reduced by:

Decreasing Schiff’s reagent time

Skipping the hematoxylin step

Omitting the oxidation step

Using chromic acid instead of periodic acid

25 / 30

Category: Clinical Laboratory

In renal pathology, PAS helps visualize:

Immune complexes

Hemoglobin casts

Tubular lipid deposits

Glomerular basement membranes

26 / 30

Category: Clinical Laboratory

Which condition would show PAS-positive diastase-resistant material?

Amyloidosis

Mucin-producing adenocarcinoma

Glycogen storage disease

Fungal infection

27 / 30

Category: Clinical Laboratory

What is the primary purpose of PAS staining?

Identify carbohydrates (glycogen, mucin, fungi)

Detect lipids

Stain nucleic acids

Highlight collagen fibers

28 / 30

Category: Clinical Laboratory

Which structure would NOT stain with PAS?

Glycogen

Thyroid colloid

Elastic fibers

Russell bodies

29 / 30

Category: Clinical Laboratory

Which fixative is BEST for preserving glycogen for PAS staining?

Carnoy’s fluid

10% neutral buffered formalin

Zenker’s fixative

Bouin’s solution

30 / 30

Category: Clinical Laboratory

What color do PAS-positive structures typically stain?

Blue

Yellow

Green

Magenta/red

Your score is

The average score is 48%

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Read Full Article: Periodic Acid-Schiff (PAS) Staining 50 FAQ and 30 MCQs

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