Interpretation in pathology Flashcards
(62 cards)
1
Q
What are pathological lesions?
A
- are morphological changes in a tissue, caused by disease or trauma
- this may be significant or incidental
2
Q
Other changes can occur in tissues which may be confused with pathological lesions what are examples of these?
A
- agonal changes (in and around the time of death)
- post mortem changes
- iatrogenic changes (clinical procedures)
- variations in anatomy
3
Q
What is gross pathology?
A
- the recognition and description of macroscopic, morphological changes to tissues and organs in the live or dead animal at biopsy, surgical removal or post mortem examination (PME)
4
Q
What are the 4 potential outcomes of gross pathology?
A
- definitive diagnosis based on appearance alone
- determine potential problem which may correlate with clinical signs an support a presumptive diagnosis
- suggest pathogenesis or mechanism of a disease
- changes not distinct enough to establish a diagnosis = further tests required
5
Q
A pathologist needs to determine if the change is significant or incidental - what is a significant change?
A
- contributed to pathogenesis/ clinical signs/ morbidity/ mortality in the case
6
Q
What is an incidental change?
A
- unrelated to the case, found as a result of the examination and/or sampling
7
Q
Incidental changes may be related to signalment - what are examples of this?
A
- species/strain/breed related changes
- age related changes
- sex related changes
8
Q
Incidental changes may be coincidental findings - give an example of this:
A
- discovering a neoplasia in an animal killed by a traumatic injury
9
Q
How may be go about interpreting the significance of gross changes?
A
- may need to undertake further examination such as histopathology (microscopic examination)
- need to be interpreted in the context of the case history
10
Q
What are agonal changes?
A
- changes that occur at or around the time of death
- often due to mechanism of death
11
Q
What are examples of agonal changes from barbital euthanasia?
A
- splenic congestion
- pulmonary oedema
- barbiturate crystals
12
Q
What are post mortem changes?
A
- changes to tissues that occur after death
13
Q
Post mortem changes can vary depending on what?
A
- the condition of the carcass at death
- the environmental condition during the period between death and post mortem (post mortem interval, PMI)
14
Q
What do post mortem changes need to be differentiated from?
A
- need to be differentiated from pathological lesions
15
Q
What things do pathologists need to know before PME?
A
- the storage conditions of the body
- environmental conditions, refrigerated, frozen, exhumed
16
Q
What is algor mortis?
A
- the cooling of the body after death
17
Q
Algor mortis can vary due to what factors?
A
- species = faster in smaller animals
- site of temperature measurement
- insulation = slower in animals with lots of hair/wool/adipose tissue
- slower in herbivores (continued fermentation generates heat)
- environmental temperature conditions
- state of animal before death (haemorrhage, pyrexia, sepsis, activity before death, wounds)
18
Q
What is rigor mortis?
A
- contraction of the muscles after death
19
Q
What causes rigor mortis?
A
- due to the lack of ATP to allow the breakdown of crosslinking in muscle fibres
- subsides with autolysis of the muscle
20
Q
Where is rigor mortis absent?
A
- in emaciated animals (lack of muscle mass)
- or in very cold conditions (may be confused with freezing)
21
Q
When is rigor mortis more rapid?
A
- rapid if there is activity before death
e.g., seizure, struggle
22
Q
In what circumstance may rigor mortis be instantaneous?
A
- electrocution
23
Q
What is livor mortis?
A
- the sinking of blood in vessels
- can see body position when dead or if a body has been moved
24
Q
In livor mortis how does blood pool?
A
- pool sites are dependent due to gravity
25
The blood in livor mortis does what after a period of time?
- eventually sets so the pattern will remain despite moving the body after death
26
What should you check to make sure your not seeing hypostatic congestion (livor mortis)?
- should always check for symmetry when you see a colour change
27
How would you differentiate between hypostasis (livor mortis ) and bruising?
- bruising is outside the vessel
- hypostasis is blood sinking in the vessel
28
What are post mortem blood clots like?
- will not be adhered to vessel walls and they form coasts of the vessels in which they are found
- pale portion (chicken fat clot)
- red portion (red current jelly clot)
29
What are ante mortem thrombi like?
- thrombi in arteries will be attached to the artery wall, are often dry and taper off in the direction of blood flow before death
- venous thrombi may be attached to the vessel wall but may resemble post mortem clots
30
What is bloating?
- gaseous distension of the gastrointestinal tract due to the production of gas by microbial activity
31
What problems can bloating cause in a PME?
- can squish the organs and change what we are trying to interpret
32
What is taphonomy?
- the study of the processes that affect the decomposition, dispersal, erosion, burial and re-exposure of organism after, at and even before death
33
What is autolysis?
- breakdown of tissue as a result of enzymes contained within cells = self-digestion
34
What is putrefaction?
- breakdown of tissue by microbial action
35
What are forms of decomposition?
- scavenging
- desiccation and mummification
= both forms of decomposition
36
What are the classical stages of decomposition?
1. fresh
2. primary bloat
3. activate decay
4. advanced decay
5. skeletonization
37
What is desiccation and mumification?
- loss of water from tissues exposed to air after death
38
What body parts are most susceptible to desiccation and mummification?
- eyes and mucous membranes
39
What organ desiccates more slowly?
- skin
40
What conditions are required for mummification?
- can occur with low humidity and adequate ventilation
41
What is forensic entomology?
- predictable colonisation of a cadaver after death in different environments by different invertebrate life stages and species
42
What is the best way to identify post mortem interval?
- forensic entomology
43
What can forensic entomologists provide?
- advice for sampling - live and preserved samples
- can be a data logger (left at the scene to provide data for interpretation)
44
What are the limitation of forensic entomology?
- educator of investigators - entomological evidence collection
- absence of invertebrates in some cases or loss during body recovery
- lack of environmental/meteorological data for a scene
45
Biochemistry and microbiology is ongoing research what could it be used alongside or replace in the future?
- forensic entomology
46
INFO CARD:
Biochemistry:
- large number of parameters to choose from
- requires standardisation and validation
Microbiology:
- exciting prospects for PMI and other forensic applications
47
What are pigments due to post mortem changes?
- haemoglobin imbibition
- bile imbibition
- pseudomelanosis
48
What is haemoglobin imbibition?
- staining of tissues by haemoglobin pigment due to erythrocyte rupture after death
49
What is bile imbibition?
- staining of tissues by bile pigment leach out from the gall bladder after death
50
What is Pseudomelanosis?
- blue-green/green-black discolouration from hydrogen sulphide created by putrefying bacteria
50
What is normal colour determined by?
- innate colour and number of cells
- special pigments
- adipose tissue
- amount of blood in the vascular bed
51
What is the pigment : tissue ratio like in dark tissues?
= high pigment to tissue ratio
52
What is the pigment : tissue ratio like in light tissues?
= low pigment : tissue ratio
53
Pigments can be split into what?
- endogenous
- exogenous
54
Haemorrhage (extravasation of RBCs), congestion, lysis of RBCs, and aging bruises can impart what pigment?
- red-brown, green and yellow pigments to tissues (dependent on stage of process)
55
What is icterus?
- Staining of tissues yellow by bile pigments due to pre-, intra- or post-hepatic causes
56
Some drugs can cause staining - give an example:
- e.g. tetracycline discolouring developing teeth and bones
57
How can fibrosis cause pigment loss?
- Loss of tissue pigment due to replacement with fibrous connective tissue
58
Melanin pigment may be present as part of normal colouration, in discrete areas (melanosis) - where can it be increased or decreased?
- increased or decreased as part of some inflammatory changes, or tumours (melanoma)
59
Fungi, bile, eosinophil infiltrates can cause what discolouration?
- green discolouration to tissue
60
Carotenoids can cause what discolouration?
- Yellow discolouration to plasma and lipid laden cells
61
where can tattoos, carbon and other dusts be found in the body?
- Can be present in tissues and migrate to local lymph nodes
