Special Stains and Cell Blocks/Biopsies

what do special stains stain?

stain extracellular components → variety of fixatives depending on which special stain (also each stain looks different)

what does IHC stain?

stains for antibody reactivity → look for certain genes or genetic mutations

• stain nucleus, cytoplasm, nuclear membrane, cytoplasmic membrane

• formalin is the fixative of choice, also 95% ethanol

special stains can be used for …

• detecting microorganisms

• differentiating pigments

• evaluating evidence of differentiation

• also help with rapid diagnosis and timely and appropriate treatment

what is a trichrome and what was it used for?

• has 3 dyes

  • cytoplasm, keratin, and muscle fibers → red

  • collagen and muscle → blue

  • fixative → 95% ethanol or Bouin’s solution

• used to stain CT → differentiates skeletal and smooth muscle, non-muscle fibers, and collagen

what are some nuclear stains?

• fuelgen stain → stains nuclei violet/blue (no fixative needed)

• biebrich scarlet → stains barr bodies red w/ green bg → 95% ethanol

• acetic orcein → shows chromatin → stains red

why only stain nuclei of cells? (Fuelgen stain)

to determine which nuclei are atypical/abnormal :]

what kind of pigments are there?

endogenous and exogenous

what is an endogenous pigment?

• pigment/substance is coming from within the body (internally formed)

  • ex: melanin → made by melanocytes

what is an exogenous pigment?

• pigment/substance is coming from outside the body (externally formed)

  • ex: carbon pigment from smoking

types of pigments

• bile

• hemosiderin

• carbon

• melanin

• lipofuscin

bile

from liver, pancreas, biliary tract, gall bladder → stains green/gold

hemosiderin

• blood

• common in pulmonary tract → stains green/refractile brown

carbon

• from smoking or air pollution, commonly found in the pulmonary tract

• stains black

melanin

• from melanocytes or melanoma → stain dark brown

lipofuscin

• composed of lipid-containing residue from lysosomal digestion

• found in liver, prostate, and other areas, often in elderly patients

• stains yellow brown

describe prussian blue (iron stain)

• used to show hemosiderin laden macros

• stains hemosiderin particles deep blue within the cytoplasm of the macros

• fixative → 95% ethanol or formalin

describe fontana masson

• historic stain → not really used now

• stains melanin and argentaffin granules → granules found in the GI tract which help with digestion

• stains granules black

• fixative → formalin (alcohol dissolves granules)

what is the benefit to staining cell products?

• identify cell type

• determine the primary site of a metastatic malignancy

• assess the diff. of a malignancy

• detect potential cause of various conditions that can drive patient treatment

what cell products can be stained?

• lipid

• mucin

• glycogen

• amyloid

lipid

• help identify a renal primary

• diagnose lipid pneumonia

• present in lipomas and liposarcomas

mucin

• support glandular diff.

• found in much of the pulmonary and GI tracts

• present in cell walls of fungal organisms

glycogen

• must diff. glycogen and mucin

• present in normal kidney and gyn tract

• used to identify/diff. certain types of microorganisms

amyloid

• presence confirms amyloidosis

• requires special polarized scope to visualize + staining

what stains are used for lipids?

• oil red o

• sudan black

oil red o

• stains neutral fat in cytoplasm

• used to diagnose lipid pneumonia → lipids going into airways by burping, bile, or car crash victims→ mostly seen in infants

• mostly used compared to sudan black

• fixative → air drying (preferred) or formalin

• fat droplets stain red and nucleus stains black

sudan black

• used for identifying lipid

• fixative → formalin, air drying, gluteraldehyde

• results in black deposits within the cytoplasm where lipid used to be

• mostly used for histology/tissues

what stains are used for mucin?

• mayer’s mucicarmine

• alcian blue

mayer’s mucicarmine

• stains epithelial mucin and the capsule of cryptococcus

  • mucus → deep rose

  • nucleus → dark

  • all other elements → faded yellow

• fixative → 95% ethanol and formalin

alcian blue

• stains weakly acidic substances (sulfacted mucosubstances) such as hyaluronic acid

• sulfated mucosubstances → blue

• counterstain → pink

• fixative → 95% ethanol

what does pink mean in mucicarmine and alcian blue?

• pink in mucicarmine → positive

• pink in alcian blue → negative

PAS

• demonstrates glycogen (but also stains mucin)

• deep rose stain

• fixatives → air drying, 95% ethanol, formalin, NOT gluteraldehyde (used for electron microscopy)

• special note → two preps are made → one is treated with diastase to determine if substance is glycogen or mucin

• if pink stays → mucin if pink goes away → glycogen

congo red

• demonstrates amyloid → normal protein found in tissues (when abnormally growth is seen → called amyloidosis)

• deep pink to red color

• apple green color seen with a polarizing filter

  • nucleus → blue

• fixative → 95% ethanol

what stains are used for microorganisms?

• AFB

• silver stain or GMS

• PAS → many mycoses have a mucin capsule or a carb rich cell wall surrounding the organism

AFB

• geimsa stain

• gram stain

• used for bacteria

• two types → ziehl neelson and fite

• detects presence of acid fast bacilli

• acid fast organisms contain large amounts of lipid in cell wall

• stains reddish-pink

• fixative → air drying

GMS (silver stain)

• stains cell walls of fungus

• contains large amounts of polysaccharides that react with the stain, reducing it to metallic silver

• fungi → sharp delineation pale grey or black

• mucin → pale grey

• background → greenish

• fixatives → 95% ethanol or air drying

what organisms can you see with GMS?

• coccidioides → found in southwest area of USA

• nocardia

• histoplasma