Lesion descripton and recognition

Question 0

What characteristics need to be described on a lesion?

Answer 0

Where is it?
Size
Shape
Colour
Consistency
Odour
Any special features
examine the cut surface

Question 1

What is the initial step in examining a specimen?

Answer 1

Identify the species and the tissue/organ

Question 2

What terms can be used to describe where the lesion is?

Answer 2

Focal- one part Multifocal to coalescing- multifocal join up
Solitary Segmental- portion of a tubular organ
Multifocal Miliary- multiple small lesions
Diffuse- whole organ

Question 3

Why are size and weight of the lesion important?

Answer 3

Size can be given as a linear measurement in two or three dimensions and the proportion of the organ affected should be given.
Weight- must be relative to the weight of the animal.
Volume- again only relevant if the weight of the animal is known.

Question 4

What terms can be used to describe the shape of a lesion?

Answer 4

Circular, oval, nodular. Comment on the borders- well/poorly defined, demarcated and the surface:
flat (flush with the surface)
elevated, depressed umbilicated, pedunculated (lipoma), sessile (wide base attachment)

Question 5

How should colour be described?

Answer 5

primary colour plus light/dark, shiny/dull

Question 6

What are the criteria looked for in judging the consistency of a lesion?

Answer 6

type: soft, firm, hard
degree: slight, moderate, marked
cohesion: friable, elastic

Question 7

Give an example of the odour of a lesion being important?

Answer 7

Ammonia on the breath- kidney disease

Question 8

What do you look for in surface features and the cut surface?

Answer 8

1) free fluid, blood, exudate

2) consistency, amount of blood, capsule or borders to the lesion once into the organ.

Question 9

What do you do if the whole lesion cannot be submitted to the lab?

Answer 9

Send a portion but with a diagrammatic representation of the lesion.

Question 10

What two types of spread of a lesion are there?

Answer 10

Haematogenous/systemic- if the lesions are spread evenly throughout the organ.
Aerogenous portal of entry- e.g. in the cranioventral regions of the lungs.

Question 11

What does a raised lesion suggest?

Answer 11

That something has been added. e.g. a parasite with surrounding inflammation- Muellerius capillaris in sheep lungs.

Question 12

What do depressed lesions imply?

Answer 12

Something has be lost e.g. due to necrosis, traction on adjacent tissue by scar tissue or collapse of the lung.

Question 13

What do flat lesions imply?

Answer 13

An acute process has occurred where has not been time for cells/fluid to accumulate.

Question 14

How does demarcation vary between lesions?

Answer 14

Benign tumour- well demarcated because it grows by expansion
Inflammatory lesions- if the are chronic they are surrounded by fibrosis so are well demarcated whereas an acute lesion will be poorly demarcated.

Question 15

Why the the size of the lesion important?

Answer 15

Particularly if you are submitting only part of the lesion to a lab. It is also important for assessing the functional significance e.g. one small abscess in the liver is not as significant as complete hepatic fibrosis that affects the whole organ.

Question 16

What is the significance of an organ being red/black in colour?

Answer 16

Due to an increase in the amount of blood and can indicate congestion or haemorrhage. If the haemorrhage is significant it will be very dark (deoxy Hb) and will be most obvious in light coloured tissue e.g. brain vs spleen. If there is also a nodular lesion then consider a haematoma or vascular lesion.

Question 17

What this the significance of a black/brown colour?

Answer 17

Melanin, exogenous carbon, putrefactive bacteria, haemosiderin.
If it is a mass- melanoma (melanoma containing neoplasm)
Black and not raised- melanosis
PM change- pseudomelanosis
Haemosiderosis- old congestion

Question 18

What is the significance of a green colour?

Answer 18

Usually a bile pigment seen in areas of the liver and the intestine adjacent to the gall bladder. Some fungal pathogens in the resp tract have this colour.

Question 19

What is the significance of a yellow colour?

Answer 19

fat, bile pigment (bilirubin), fibrin, cellular exudates, neoplams or due to icterus (biliverdin) or lipidosis.

Question 20

What is the significance of the colour white?

Answer 20

Exudates/neoplasia or CT

Question 21

What are the possible causes for fluid around a lesion?

Answer 21

oedema (clear), serofibrinous (inflammatory), urine, turbid fluid (cellular elements, inflammation, lymphatics or neoplastic effusion),
blood.

Question 22

When is a lesion described as soft?

Answer 22

Normal consistency for many tissue- those with little stroma or loosely organised.

Question 23

When is a lesion described as firm?

Answer 23

Normal in fluid-poor, cell rich tissues. Seen in many inflammatory or proliferative lesions and any addition of scar tissue.

Question 24

When is a lesion described as hard?

Answer 24

It implies mineral density e.g. cartilage, bone or mineral deposits.

Question 25

When is a differential diagnosis simple?

Answer 25

If based on the gross appearance of the lesion e.g. fractured femur or ruptured spleen (trauma associated)
Or when there are pathognomic lesion (associated with a particular disease).

Question 26

When is a differential diagnosis not simple?

Answer 26

When the lesion is not pathognomic. e.g. a solitary mass can be a focus of inflammation, a neoplasm, a haematoma or a cyst. Examination as prev. described will narrow down what the lesion is.
But sometimes you will require histology.

Question 27

How can lesions not appear as they seem?

Answer 27

Tumours can show ulceration as their dominant feature rather than proliferation.
Or necrosis, abscessation and inflammation within a bulk of a tumour can occur as they cut off their own blood supply.