Using the Pathologist

Question 1

What are the key features to distinguish neoplasia?

Answer 1

-

Question 2

Define neoplasia

Answer 2

• uncontrolled proliferation of cells- proliferation continues in abscence of inciting cause neoplastic cells originate from a single cell (has undergone mutation and lost the ability to control its division)

Question 3

Define hyperplasia

Answer 3

Proliferation of cells that stops when inciting cause is removed

Question 4

What does current research show neoplastic cells may be ?

Answer 4

2 types of cells not just monoclonal

Question 5

How do benign tumours grow? How do they appear clinically and pathology?

Answer 5

• slowly by expansion- well demarkated from surrounding tissue (may be compressed)- surrounding tissue capsule- freely mobile on palpation- uniform cut surface (may contain cysts) - little hamorrghage or necrosis

Question 6

What is a haemangioma?

Answer 6

benign tumour of the blood vessel wall endothelium

Question 7

Microscopic features of benign tumours?

Answer 7

• cells similar to tissue of origin- well organsied - share the functional purpose of tissue- contained in capsule- cells not mitotically active - little evidence of 2* change (haemorrhage or necrossi)

Question 8

Characteristics of malignant tumours

Answer 8

• grow by invasion- not encapsulated- not mobile on palpation - complete removal difficult- often ulcerate if on skin or mucosa- recurs after removal- surface necrosis and naemorrhage- METASTASIS

Question 9

Which breed are predisposed to hamemangiosarcoma?

Answer 9

GSD

Question 10

Microscopic feeatures of malignancy?

Answer 10

• pleioporphism (different looking cells)- anisokaryosis (differnet sized nuceli?)- ^ nucleus:cytoplasm ratio- normal/abnormal mitoses- loss of cohesiveness and structure- malignat fusion -> syncitia- 2* changes (necrosis inflamm etc.)- not encapsulated/extending beyond the capsule

Question 11

Name some benign tumours of epithelial origin

Answer 11

> surface or non-glandular epithelia = papilloma> glandular epithelia = adenoma

Question 12

Name the main types malignant tumours of epithelial origin

Answer 12

> epithalial = carcinoma> glandular epithelia = adenocarcinoma

Question 13

What is the suffix for mesenchymal origins?

Answer 13

• benign = -oma- malignant = -sarcoma

Question 14

What is the exception to the -oma tumour rule?

Answer 14

• Granuloma - not a tumour! Just chronic inflammation

Question 15

What are lymphomas?

Answer 15

• tumouro fthe lymphoid system = MALIGNANT!

Question 16

What are melanomas?

Answer 16

Benign OR malignant tumour or melanocytes

Question 17

What are mastocytomas?

Answer 17

Can be benign or malignant mast cell tumours

Question 18

What are leukaemias?

Answer 18

tumours derived from cells of bone marrow, circulate in the blood

Question 19

What are sarcoids?

Answer 19

low grade fibrosarcomas commonly seen in horses (bovine papillomavirus infection)

Question 20

What are the 4 routes of metastasis? Which tumours spread this way?

Answer 20

> lymphatic- carcinoma- LNs draining tumour contain 2* deposits > vascular - sarcoma- tumour seeds widely to internal organs (liver and lungs, multiple 2*) >trans-cavity- mesothelioma or ovarian neoplasia- spread acorss serosial surfaces eg. effusion > local - multiple tumour types - spread along fascial planes

Question 21

WHat are multicentric tumours?

Answer 21

eg. lymphoma- difficult to determine primary site

Question 22

Which malignant tumours are most likely to metastasise rapidly and constantly?

Answer 22

• tonsillar carcinomas- pancreatic carcinomas- osteosarcomas- oral and digital melanomas- mammary carcinomas (cats)

Question 23

Which malignant tumours metastasise slowly or rarely?

Answer 23

• squamous cell carcinomas- fibrosarcomas > invade locally, recurr but not liekly to metastasise

Question 24

How may immunohistochemistry be used to dx tumour?

Answer 24

• poorly differentiated tumours cannto be IDed on morphological grounds alone- cell surface markers eg. cytokeratin, B/T cell lymphomas

Question 25

Which lymphoma has better prognosis?

Answer 25

B cell (T cell responds less well to chemotherapy)

Question 26

What is tumour grading?

Answer 26

Carried out by pathologist- high grade = poor prognoses and vice versa

Question 27

Methods of tumuour grading?

Answer 27

> light microscopy (SCC)- how closely does it resemble the parnent tissue? low grade = keratin pearls due to excessive keratin production. high grade cannot see keratin so much. > Immunophenotyping (lymphoma) - less CD3 (weaker staining) = HIGH GRADE > detecting genetic mutations (lymphoma) - standard practice in human medicine - tailor tx to individual tumours > proliferation markers (MCT)- eg. Ki-67 (showing mitosis levels) score

Question 28

How should a “representative sample” be obtained to send to the pathologist?

Answer 28

> inicsional- include margin normal tissue- avoid necrotic and cavitated areas (EXCEPT for bone tumours where sample of maximal bone lysis is helpful) - mark margins of interest- ID smaples from different sites- include imagine data - fix properly (neutral buffered formalin at least 4:1 ratio)- smaller that 2cm sample- dont hurt mailman