Chapter 20: General Principles of Biopsies

Question 1

What are the 2 main types of cutting needles for needle-core biopsies?

Answer 1

• Tru-Cut needles - Hand powered and automated version
• Franklin-Silverman needle - weird split needle design

Question 2

To what depth should a biopsy needle be placed into the tissue?
How should the sample be removed from the needle?

Answer 2

• At least 1.5cm into tissue of interest
• Sample removed with a 25g needle

Question 3

What are the three main aspiration needle-core biopsy needles?

Answer 3

• 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

Question 4

What is a vacuum-assisted needle-core biopsy device?

Answer 4

Similar to Tru-Cut but with the addition of a vacuum

Question 5

How often to needle-core biopsies get a diagnosis?
How often does this diagnosis agree with surgically obtained biopsies?

Answer 5

• TruCut is diagnostic in 40-97%
• Agrees with surgical biopsy in 54-94%

Question 6

What range of sizes of punch biopsies are available?

Answer 6

1 to 8mm

Question 7

What is the recommended location when obtaining an incisional biopsy?

Answer 7

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

Question 8

Name the following instruments:

Answer 8

A - Laparoscopic cup biopsy forceps
B - Laparoscopic punch biopsy forceps

Cup forceps will tear whereas punch forceps will cut

Question 9

Name the following instrument and its component parts

Answer 9

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

Question 10

How do pre-treatment biopsies compare with post-excision histology in soft tissue sarcomas?

Answer 10

• 60% are in agreement
• 30% underestimate the grade
• 10% overestimate the grade

Question 11

What are the three options for obtaining lymph node biopsies (think abdominal nodes)?

Answer 11

• Excisional
• Guillotine (if full excision risks potential vascular damage)
• Laparoscopically with cup forceps

Question 12

How often does sentinel lymph node mapping alter treatment in dogs with MCT?

Answer 12

42% of the time

Question 13

What is the main concern regarding thyroid biopsies?

Answer 13

• Highly vascular - ultrasound guidance necessary, if freely movable consider excisional biopsy
• cytology also often diagnostic

Question 14

Can you use an automated TruCut biopsy device to biopsy the liver in cats?

Answer 14

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

Question 15

How do hepatic needle core biopsies compare with wedge/guillotine biopsies?

Answer 15

48% agreement between needle-core and wedge
- 83.3% needle-core biopsies are diagnostic quality compared to 100% guillotine

Question 16

How many samples are recommended when taking endoscopic biospies of the GIT?

Answer 16

• 6-8 gastric
• 10-15 small intestinal
• 3-5 large intestinal

This will only sample a portion of the mucosa!

Question 17

What is the rate of final diagnosis with surgical GIT biopsies?

Answer 17

94%

Question 18

List indications and contraindications to renal biopsy?

Answer 18

Indications:
- glomerular disease
- Acute, unresponsive renal failure

Contraindications:
- bleeding disorders
- severe anemia
- uncontrolled hypertension
- pyonephrosis or abscess
- hydronephrosis

Question 19

What tissue is recommended to be obtained in a renal biopsy? Why?

Answer 19

Cortical tissue only.
Sampling of the medulla significantly increases the risk of hemorrhage as well as infarction and fibrosis

Question 20

What are the options for obtaining a renal biopsy?

Answer 20

• Needle-core biopsy (14g and vacuum-assisted obtain larger samples)
• Surgical wedge biopsy - often requires temporary vascular occlusion

Question 21

List the risks associated with a renal biopsy?

Answer 21

• Hemorrhage (10% dogs, 15% cats)
• AV fistula
• Cyst formation
• Infarction
• Thrombosis
• Infection
• Fibrosis
• Rarely hydronephrosis and death (usually from clot obstruction of ureter)

Question 22

Where is the ideal location for a pancreatic biopsy? Why?

Answer 22

Right distal limb
Far away from pancreatic ducts and duodenal vasculature

Question 23

What is the rate of diagnostic sampling of CT-guided biopsy and FNA for thoracic masses?
Associated complications?

Answer 23

• 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

Question 24

What are the ligation/sealing options for obtaining a lung biopsy?

Answer 24

• Suture ligation
• Stapler
• bipolar device (LigaSure - only if <3cm from the edge)

Question 25

What are the 2 instrument options for a bone biopsy?

Answer 25

• Jamshidi needle
• Michele trephine (increased risk of pathological fractures due to size)

Question 26

How should biopsy tissues be processed?

Answer 26

• 10% neutral buffered formalin in a 1:10 sample to formalin ratio
• Eyes should be placed in Bouin’s fluid

Question 27

How can second opinion histopathology effect the results?

Answer 27

• 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)