L14 - Role of Pathology in the Diagnosis & Management of Neoplastic Diseases

Question 1

What are the most common benign and malignant breast neoplasms?

Answer 1

• The most common benign breast neoplasm is a fibroadenoma

- The most common malignant breast neoplasm is a breast carcinoma

Question 2

Give an example of a palpable difference between benign and malignant breast neoplasms.

What is the cause of this difference?

Answer 2

• Benign breast neoplasms are mobile whereas malignant breast neoplasms are rarely mobile
• This is because the malignant breast neoplasm is able to invade surrounding structures

Question 3

In which layer of the colon do the majority of neoplasms arise and why?

Answer 3

The majority of colon cancers arise in the mucosa. This is because:

1 - It is the region exposed to the highest concentration of carcinogens

2 - It is the region with the highest turnover rate

Question 4

Why might colon cancer cause a change in bowel habit?

Answer 4

• Colon cancer can be stenosing
• This can slow the passage of the stool through the colon, allowing for more time for water reabsorption, causing constipation
• It can also obstruct solid matter from passing through the colon whilst permitting liquids to pass, causing diarrhoea

Question 5

Which section of the colon is most commonly affected with a colon carcinoma that causes a change in bowel habit?

Why?

Answer 5

• Colon carcinomas affecting the sigmoid colon more commonly cause a change in bowel habit
• This is because colon carcinomas of the sigmoid colon are more frequently stenosing, whereas colon carcinomas in the ascending colon are more frequently polypoid

Question 6

List 3 biopsy techniques.

Answer 6

1 - Endoscopic biopsy (e.g. GI tract and bronchi)

2 - Needle biopsy (many areas)

3 - Punch biopsy (e.g. skin)

Question 7

List 4 techniques that are used to obtain cytology specimens.

Answer 7

1 - Smears

2 - Endoscopic brushings

3 - Bodily fluids

4 - Fine needle aspiration

Question 8

What are the purposes of pathological assessments of cancer?

Answer 8

1 - To confirm the diagnosis of a malignancy

2 - To determine the aggressiveness (grade) of a cancer

3 - To assess the extent of spread (staging) of a cancer

4 - To examine the completeness of excision

Question 9

What is the most common distant site of spread of colorectal cancer?

Why?

Answer 9

• The most common distant site of spread of colorectal cancer is the liver
• This is because the cancer is able to reach the liver directly by the hepatic portal vein

Question 10

How can an inflammatory infiltration be told apart from a neoplastic infiltration histologically?

Answer 10

• An inflammatory infiltration consists of a mixed population of cells
• A neoplastic infiltration consists of a pure population of cells

Question 11

Give an example of an immunohistochemical prognostic marker for cancer.

How does it work?

Answer 11

• The Ki-67 labelling index is used as a prognostic marker for cancer
• It detects various components of the cell cycle
• The higher the labelling, the more rapid the turn over, indicating high metastatic potential

Question 12

How can immunohistochemistry be used to identify therapeutic options for cancer?

Answer 12

• Expression of specific antigenic markers can be used to identify tumours that are likely to be amenable to specific therapies targeting the antigens expressed. For example:

1 - Breast carcinomas that express the growth factor HER2 can be treated with herceptin, a HER2 antagonist

2 - Breast carcinomas that express the oestrogen receptor may be amenable to hormone therapy

3 - GI stromal tumours expressing the tyrosine kinase receptor c-KIT can be treated with Gleevec, a tyrosine kinase inhibitor

*Identifying mutations can also impact therapeutic options

Question 13

List 2 examples of how fluorescence in-situ hybridisation (FISH) can be used to identify a neoplasm.

Answer 13

1 - FISH can be used to identify kappa and lambda light chains to demonstrate clonality in plasma cell infiltrates (this can also help tell apart an inflammatory from a neoplastic infiltration). E.g. a neoplasm of B cells will have a whole population of only kappa or only lambda, whereas a normal population of B cells will be heterogeneous

2 - FISH can be used to identify Epstein-Barr virus encoded RNAs (EBERs) to identify EBV-related neoplasms

Question 14

What is post-transplant lymphoproliferative disease?

Answer 14

• Spectrum of disease occurring during immunosuppression
• Majority related to EBV infection -> virus affects B cells & remains in latent phase, controlled by EBV-specific T response -> immunosuppression interferes with T cell function -> uncontrolled proliferation of EBV-infected B cells