L1: Intro To Cytology In Vet Practice Flashcards
Cytopathology =
The study of CELLULAR disease and the use of cellular changes for the diagnosis of disease
Meeting cytology goals relies on:
- nature and distribution of lesion
- proper collection technique, slide prep, and staining
- skill/experience of the cytologist
Considerations prior to sample collection:
- signalment
- presence of inflammation/infection and/or infection (avoid!)
- exfoliation of lesion (low cellularity, presence of significant blood)
- platelet function and coagulation
- clinical diagnosis
Boxers prone to mast cell tumors
:(
Advantage of cytology over histo
- easier to collect
- less discomfort
- less likely to result in serious complications
- costs less
- faster turn around time
Advantages of histo over cytology
- gold standard b/c more tissue architecture present
- better for poorly exfoliative lesions
- more definitive diagnosis (preserves tissue architecture, and can differentiate b/w inflammatory and neoplastic changes)
How can inflammatory slide look neoplastic artificially?
neutrophils release myeloperoxidase on top of normal cells, making them look ugly and neoplastic
Cases in which cytology not the best:
- low cellularity or hemodilute sample
- thick preparation
- not representative of lesion
- rough handling
- mixed cell populations
- lesions requiring tissue architecture
- mammary tissue
Cytology may be used in 2 ways:
Diagnosis
Screening
Types of cytology samples
- fluid samples
- tissue aspirates
- tissue scrapings
- tissue imprints
General indications for the use of diagnostic cytology
- effusions
- urine sediments
- prostate (direct aspirate, washing)
- lymphadenopathy
- exam. Of metastatic disease
- diffuse organomegaly
- cutaneous/subcutaneous mass/lesion
- conjunctival/vitreous/aqueous cytology
- pulmonary/nasal aspirates/brushings
- bronchoalveolar/nasal washing/lavage
- abd. Mass
- intraoperative mass or lesion
Anything in formalin is histopath!!
:)
“Cytology kit” collection supplies
- 22-25 g needles
- 3-6 mL syringes
- glass slides w/ frosted edge
- pencil
- scalpel blade
- fluid samples: purple top for cytology, red top for culture***
- don’t put urine in red tops - silica can interfere with sediment
Sample handling of fluids
- made glass slide at time of collection**
- refrigerate fluid sample (not slides)
- process ASAP to preserve cell counts/morphology
- special requirements for BAL and CSFs
2 tissue aspiration techniques
Needle attached or not attached to syringe. Attached better for larger masses, masses that are difficult to exfoliate, or cutaneous/SC masses. Needle w/o attached syringe allows for better control w/ smaller masses, is less traumatic, and good for masses in all layers including intra-abdominal
Suction vs. no suction?
Suctioned sample can be more blood contaminated but may be necessary for firm masses.
no suction can get a small core of tissue by rotating needle and is useful for highly vascularized organs (LIV, SP)
Nuclear streaming
Results from ruptured cells due to excessive tissue handling
-common with lymphoma cells( they are fragile)*
Sample handling of slides
- air dry; don’t heat fix
- store covered at room temp
- submit 4-6 slides
- ship cyto and histo samples separately (even formalin fumes can destroy cyto)
- plastic/styrofoam slide mailers preferred to cardboard
Cytology sample expsed to formalin will look:
BLUE
best Diff Quik procedure
- fix for at least 2 minutes
- contact time more important (so don’t need to dip)
- rinse with DI water
- if over/understained without oil: possible to remove color by putting back in methanol for 30 minutes, then going through other 2 stains again; can add more color
- some cells may not stain well (ie. Mast cells)
Necessary clinical history
- signalment
- lesion description including location, size, gross appearance, consistency, attachment, duration/changes, organ enlargement
- medications
- other clinically relevant history (previous neoplasms or infections)
- clinical diagnosis/impression
Site predilections of common tumors
Epidermis:
-SCC
Mostly in Dermis:
- PCT
- Histocytoma
- Melanoma
- Lymphoma
- TVT
Dermis/Subcutis: MCT
Subcutis: lipoma, hemangiopericytoma cell tumor
Cytology =
Cells on a glass slide WITHOUT retained tissue architecture (limiting factor)
- practical in-clinic diagnostic tool
- aids in prognosis, helps direct therapy
- not always diagnostic
