Sample Collection, Fixation, and Staining Flashcards
What are the techniques that can be used to collect a sample from a lesion
FNA
Impression
Core Biopsy
Incisional Biopsy
Excisional Biopsy
What is the most common fixative
10% neutral buffered formalin
What are the main objectives of fixation
Prevent autolysis
Prevent putrefaction
Insolubilize tissue
Harden tissue
What are some drawback of NBF
Hazardous
Kills bacteria–samples can’t be used for cultures
Damages nucleic acids–samples can’t be used for PCR, etc
What is the maximum thickness of tissue that NBF can effectively fix?
0.5cm
What is formalin:tissue ratio
10:1
How long does it take for tissues to be fixed
24 hours
What is the most common stain
H&E (hemtoxylin and eosin)
Hematoxylin is…
blue, basophilic. We learned this!
Eosin is…
red, acidic
What are the pros of H&E staining
Good for basic evals
What are the cons of H&E staining
Many cells look the same
Can be difficult to determine origin of atypical cells
GMS or PAS stains…
Fungi
Acid-fast stains…
Mycobacteria
Massons trichome stains…
collagen
