ASCP Special Stains and Histochemistry

Question 1

What does the PAS (Periodic Acid-Schiff) stain primarily identify?

Accepted Answer

Glycogen, neutral mucins, and basement membranes

Answer

Nuclei and DNA

Answer

Elastic fibers

Answer

Amyloid deposits

Question 2

In a Masson's trichrome stain, what color does collagen appear?

Accepted Answer

Blue or green

Answer

Red

Answer

Yellow

Answer

Black

Question 3

Which special stain is used to identify iron (hemosiderin) deposits in tissue?

Accepted Answer

Prussian blue (Perl's stain)

Answer

Congo red

Answer

Oil Red O

Answer

Alcian blue

Question 4

What is the characteristic staining result of amyloid with Congo red?

Accepted Answer

Apple-green birefringence under polarized light

Answer

Blue birefringence under polarized light

Answer

Red fluorescence only

Answer

Negative staining

Question 5

Which stain is used to identify fungi and mucin simultaneously in tissue sections?

Accepted Answer

Both GMS and PAS

Answer

Masson's trichrome

Answer

GMS (Grocott's methenamine silver)

Answer

PAS (Periodic Acid-Schiff)

Question 6

What is the purpose of using a diastase control with a PAS stain?

Accepted Answer

To confirm that PAS-positive material is glycogen by removing it with diastase pretreatment

Answer

To enhance mucin staining

Answer

To block non-specific background

Answer

To differentiate neutral from acid mucins