Tumor diagnosis and clinical staging

Question 1

What is grading of tumors intended for

Answer 1

Grading of tumors is based on histopathology and is designed to give an indication of the malignancy of the tumor

Question 2

What are the criteria used to assign tumor grades

Answer 2

Degree of cellular differentiation

The mitotic index

The degree of cellular pleomorphism

The invasiveness of the tissue

The degree of reaction induced by the tumor

The degree of necrosis present

Question 3

Why is it important to obtain a histological grade for a tumor

Answer 3

For many tumors (especially feline lymphoma), the histological grade has been shown to affect the biological behavior of the tumor, related to factors such as:
- survival
- disease-free interval
- local recurrence
- development of metastases

Question 4

What are the two main purposes of immunohistochemistry

Answer 4

In general, immunohistochemistry serves two main purposes:
- identification of tumor type
- assessment of tumor grade

Question 5

What is clinical staging of tumors

Answer 5

Clinical staging of neoplasia determine the extent of the anatomical involvement of the neoplasm at a particular point in time
- along with the histological type of the tumor and the grade of the tumor, it provides important prognostic and therapeutic information

Question 6

What are the advantages and disadvantages of fine needle tissue sampling

Answer 6

Advantages:
- minimally invasive
- affordable
- rarely require sedation or anesthesia
- diagnosis may be rapid (best for round and epithelial cell tumors)

Disadvantages:
- small sample size may not be representative of the tumor population
- results may be nondiagnostic and delay diagnosis

Question 7

What are the advantages and disadvantages of needle-core tissue sampling

Answer 7

Advanatges:
- minimal surgical site closure (i.e., less risk of dehiscence or infection compared to surgery)
- tumor architecture and grade may be determined
- immunohistochemicaal stains and other tests possible

Disadvantages:
- sedation often required
- nondiagnostic sample if crush aretefact is present
- risk of internal organ damage or hemorrhage with automated devices

Question 8

What are the advantages and disadvantages of incisional (wedge, punch) tissue sampling

Answer 8

Advantages:
- large samples are obtaines
- tumor architecture and grade may be determined
- immunohistochemical stains and other tests possible

Disadvanatages:
- sedation or general anesthesia required
- risk of sitedehiscence
- risk of tumor spread to normal tissue

Question 9

What are the advantages and disadvantages of excisional tissue sampling

Answer 9

Advanatages:
- potentially curative
- large samples are obtained
- tumor architecture and grade may be determined
- immunohistochemical stains and other tests possible

Disadvantages:
- most invasive technique
- general anesthesia required