Chapter 20: General Principles of Biopsies Flashcards
What are the 2 main types of cutting needles for needle-core biopsies?
- Tru-Cut needles - Hand powered and automated version
- Franklin-Silverman needle - weird split needle design
To what depth should a biopsy needle be placed into the tissue?
How should the sample be removed from the needle?
- At least 1.5cm into tissue of interest
- Sample removed with a 25g needle
What are the three main aspiration needle-core biopsy needles?
- Menghini
- Klatskin
- Jamshidi
(you aspirate with a syringe in the tissue of interest)
Menghini has an external bevel whereas Klatskin and Jamshidi have an internal bevel allowing a larger sample with no increased risk
What is a vacuum-assisted needle-core biopsy device?
Similar to Tru-Cut but with the addition of a vacuum
How often to needle-core biopsies get a diagnosis?
How often does this diagnosis agree with surgically obtained biopsies?
- TruCut is diagnostic in 40-97%
- Agrees with surgical biopsy in 54-94%
What range of sizes of punch biopsies are available?
1 to 8mm
What is the recommended location when obtaining an incisional biopsy?
At the junction of mass and normal adjacent tissue
- Must consider spread of disease to uninvolved tissue
- Avoid the periphery in bone lesions as this will most likely sample reactive periosteum
Name the following instruments:
A - Laparoscopic cup biopsy forceps
B - Laparoscopic punch biopsy forceps
Cup forceps will tear whereas punch forceps will cut
Name the following instrument and its component parts
This is a self-ligating loop (SurgiTie)
- A - preformed loop
- B - Knot
- C - Nylon carrier
- D - Scored black band (where you break it off)
- E - Proximal end
- F - Optional delivery system for endoscopic surgery
How do pre-treatment biopsies compare with post-excision histology in soft tissue sarcomas?
- 60% are in agreement
- 30% underestimate the grade
- 10% overestimate the grade
What are the three options for obtaining lymph node biopsies (think abdominal nodes)?
- Excisional
- Guillotine (if full excision risks potential vascular damage)
- Laparoscopically with cup forceps
How often does sentinel lymph node mapping alter treatment in dogs with MCT?
42% of the time
What is the main concern regarding thyroid biopsies?
- Highly vascular - ultrasound guidance necessary, if freely movable consider excisional biopsy
- cytology also often diagnostic
Can you use an automated TruCut biopsy device to biopsy the liver in cats?
with CAUTION!!
One study showed mortality 20% due to intense vagotonia - this was also seen at a similar rate with semiautomated devices however there were no deaths in this group
How do hepatic needle core biopsies compare with wedge/guillotine biopsies?
48% agreement between needle-core and wedge
- 83.3% needle-core biopsies are diagnostic quality compared to 100% guillotine
How many samples are recommended when taking endoscopic biospies of the GIT?
- 6-8 gastric
- 10-15 small intestinal
- 3-5 large intestinal
This will only sample a portion of the mucosa!
What is the rate of final diagnosis with surgical GIT biopsies?
94%
List indications and contraindications to renal biopsy?
Indications:
- glomerular disease
- Acute, unresponsive renal failure
Contraindications:
- bleeding disorders
- severe anemia
- uncontrolled hypertension
- pyonephrosis or abscess
- hydronephrosis
What tissue is recommended to be obtained in a renal biopsy? Why?
Cortical tissue only.
Sampling of the medulla significantly increases the risk of hemorrhage as well as infarction and fibrosis
What are the options for obtaining a renal biopsy?
- Needle-core biopsy (14g and vacuum-assisted obtain larger samples)
- Surgical wedge biopsy - often requires temporary vascular occlusion
List the risks associated with a renal biopsy?
- Hemorrhage (10% dogs, 15% cats)
- AV fistula
- Cyst formation
- Infarction
- Thrombosis
- Infection
- Fibrosis
- Rarely hydronephrosis and death (usually from clot obstruction of ureter)
Where is the ideal location for a pancreatic biopsy? Why?
Right distal limb
Far away from pancreatic ducts and duodenal vasculature
What is the rate of diagnostic sampling of CT-guided biopsy and FNA for thoracic masses?
Associated complications?
- Diagnostic samples in 83% of biopsies and 65% FNAs.
- Complications rates were 43% (pneumothorax, hemorrhage) however none of these were clinical and no treatment was required
What are the ligation/sealing options for obtaining a lung biopsy?
- Suture ligation
- Stapler
- bipolar device (LigaSure - only if <3cm from the edge)
What are the 2 instrument options for a bone biopsy?
- Jamshidi needle
- Michele trephine (increased risk of pathological fractures due to size)
How should biopsy tissues be processed?
- 10% neutral buffered formalin in a 1:10 sample to formalin ratio
- Eyes should be placed in Bouin’s fluid
How can second opinion histopathology effect the results?
- Partially changes the diagnosis in 20-30% (grade, tumor subtype or margin evaluation)
- Completely changes the diagnosis in 10-20% (cell of origin or degree of malignancy)
