Histology Stains, Intro Final

What does PAS stand for?

Periodic Acid-Schiff

What does GMS stand for?

Grocott’s Methenamine Silver

Masson’s Trichrome is also known as:

Trichrome stain

If a PAS-D stain is ran, what also must be ran?

A regular PAS

If a PAS-D stain is positive, what would that look like?

Since diastase breaks down glycogen, areas of the slide should be without color, as the stain will not adhere to glycogen since it has been broken down by diastase

If a PAS-D stain is negative, what would that look like?

The slide will retain the deep magenta stain, as that means no glycogen is present because nothing was broken down by the diastase

What specimen types usually have a PAS stain ordered on them?

Liver/hepatocytes

Kidney

Thyroid

Skeletal muscle

The PAS stain can assess for (2):

Fungal infection (LIVING ONLY)

Glycogen storage disease

What is Alpha-1 antitrypsin and why would a PAS stain be used for this?

A liver-made glycoprotein

The mutant proteins get trapped inside the liver cells and the PAS stain will highlight these areas.

A GMS stains for what cell structure?

Polysaccharide cell wall

The GMS stain primary targets the cell wall of what?

Fungus

What are some other targets for the GMS stain?

Parasites

Viral inclusions

Bacteria

Melanin

A GMS contains:

Methenamine silver

How does a GMS stain work?

The oxidation of the polysaccharides into aldehyde groups

The aldehyde groups chemically reduce silver ions, resulting in a black metallic precipitate/pigment

The GMS stain highlights:

Fungus (ALIVE OR DEAD)

Highlight other microorganisms

What is a Gram stain?

Utilize specific stains that target peptidoglycan in the bacterial cell wall

If a Gram stain is positive, what occurs?

The multilayered peptidoglycan wall is thick, which traps the crystal violet (more purple)

If a Gram stain is negative, what occurs?

The peptidoglycan membrane is thin, so it does not retain the crystal violet stain (more pink)

What is used in a Gram stain?

Crystal violet

Gram’s iodine

alcohol

Safranin

What can a Gram stain tell us about bacteria?

Bacteria morphology

Can categorize bacterial genus and species

What is a Congo red stain?

Essential stain used to identify an accumulation of amyloid in the tissue

What is amyloid?

An abnormal clump of protein that builds up in tissues and organs

If the Congo Red stain comes back red, what does this mean?

Red indicates the presence of the amyloid

What is the main diagnosis that is made from a positive Congo Red stain?

Amyloidosis

Why is having amyloid build up bad?

It inhibits normal funciton of the tissue (can be in the brain)

What kind of stain is the congo red stain?

Metachromatic stain

What tissue is usually submitted if a provider is trying to rule out amyloidosis?

Fat pad biopsy

What is the main function of the Masson’s Trichrome stain?

Used to differentiate different types of collagen (tissue components, muscle vs. collagen)

What can the Masson’s Trichrome stain demonstrate?

Fibrosis

Muscle structure

Collagen deposition

What are the steps to a Masson’s Trichrome stain?

Iron Hematoxylin (stain nuclei)

Fuchsin stain (stain acidophilic components, like muscle)

Polyacid (differentiate and decolorize)

Fast green or aniline blue (penetrate porous collagens)

If a Masson’s Trichrome stain is pink/red, what does this mean?

Muscle fibers, keratin, cytoplasm and RBCs

If a Masson’s Trichrome is blue/green:

Collagen fibers

If a Masson’s Trichrome is black, dark blue or brown:

Cell nuclei

What are common specimens that typically have a Masson’s Trichrome stain performed?

Liver (Fibrosis/cirrhosis)

Lung (Interstitial diseases)

What does Alcian blue target?

Mucins and proteoglycans (acidic mucin and neutral mucin)

What disorder does the Alcian blue stain support in diagnosing?

Barrett’s syndrome

lung cancers

colon cancers

athersclerosis

What stain highlights myelin?

Luxol fast blue

Why is the luxol fast blue stain important (relating to the NS)?

can help diagnose de-myelinating diseases in the CNS (like MS)

Luxol Fast Blue stain cannot differentiate what?

Myelination in the PNS

If an axon becomes demyelinated, what happens?

Muscle weakness, loss of muscle tone, sensory diseases, vertigo, vision loss

What does IHC stand for?

Immunohistochemical

What are some examples of IHC stains?

Her2

PR

ER

Ki-67

Sox10 (melanoma)

CD (hematologic diseases)

IHC stains can help use to further characterize:

Lesional tissue

tummor vs. benign

ER/PR

Breast cancer

Her2

Breast, prostate cancer

CD markers

CD4/8

CD5

C10

C20

CD34

CD45

P16

HPV strain 16, SCC

P53

Indicator of dysplasia/malignancy

Ki-67

cell proliferation index

grade tumor

indicates a more aggressive cancer