Introduction To Pathology

Question 1

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

Answer 1

Focal, solitary, multifocal, diffuse, multifocal to coalescing, segmental, miliary

Question 2

What characteristics are used to describe the lesion (broadly)?

Answer 2

Size, shape, color, consistency, odor, any special features (e.g. free fluid, blood, exudates), examination of the cut surface (if available)

Question 3

What words are used to describe the shape of a lesion?

Answer 3

Flat, elevated, depressed, umbilicated, pedunculated, sessile (broad based attachment); note: borders can also be commented on - well/poorly defined/demarcated/ragged/etc.

Question 4

Sensible conclusions require knowing what information about the animal?

Answer 4

1. How the animal died (note: barbiturates used in euthanasia can have profound effects on some organs e.g. the spleen)
2. When the animal died
3. Conditions post mortem

Question 5

Multifocal lesions usually imply what?

Answer 5

Systemic/haematogenous spread

Question 6

Anteroventral lesion distribution in the lungs can imply what?

Answer 6

Aerogenous portal of entry aka inhalation of pathogen

Question 7

A raised lesion implies what?

Answer 7

Something has been added
E.g. inflammatory reaction around migrating larvae

Question 8

Flat lesions can imply what?

Answer 8

An acute process in which there has not yet been time for cells/fluid to accumulate or for cells to be lost

Question 9

Depressed lesions imply what?

Answer 9

Something is missing or has been lost.
E.g. necrosis causing an irregular or disrupted shape on adjacent tissue due to scarring, atrophy, collapsed lung

Question 10

Demarcation implies what?

Answer 10

In regard to neoplasms, benign tumors are often well demarcated due to growth by expansion.

In regard to inflammatory lesions, well demarcated lesions are surrounded by fibrosis and are therefore chronic (poorly demarcated are typically acute)

Question 11

Why is lesion size significant when submitting part of a lesion?

Answer 11

The amount of organ involved relates to functional significance

Question 12

Red or black lesions indicate what?

Answer 12

Commonly indicates an increase in amount of blood but may indicate haemorrhage or congestion (darker = more significant as less oxygenated)

Question 13

Black or brown/black lesions indicate what?

Answer 13

Melanin, exogenous carbon, putrefactive bacteria, haemosiderin
-if mass, consider a melanin containing neoplasm
-if black colored and flat, consider non-neoplastic accumulation of melanocytes
-PM change, consider pseudomelanosis
-brown to golden brown, consider old/chronic congestion or haemorrhage

Question 14

Green lesions indicate what?

Answer 14

Bile pigment, typically seen in liver and intestine adjacent to gallbladder. Some fungal pathogens have a green to green/black color

Question 15

Yellow lesions contain what?

Answer 15

Fat, bile (bilirubin), fibrin, cellular exudates, neoplasms. Diffuse yellow may be due to icterus (bilirubin) or lipidosis

Question 16

White lesions indicate what?

Answer 16

Similar to yellow lesions - exudates, neoplasia, but also connective tissue (fibrous, cartilage, bone)