Nervous system pathology 5

Question 1

Describe the two types of tumours

Answer 1

• Primary: arising from CNS cell types

- Secondary or metastatic: colonising the CNS from distant areas of primary growth

Question 2

Name 3 examples of primary CNS tumours

Answer 2

• Medulloblastoma
• Astrocytoma
• Choroid plexus papilloma

Question 3

Name 4 examples of secondary/metastatic CNS tumours

Answer 3

• Mammary adenocarcinoma
• Lymphoma
• Haemangiosarcoma
• Melanoma

Question 4

How does the distributions of primary vs secondary tumours in the CNS differ?

Answer 4

Primary: usually single masses
Secondary: multifocal distribution

Question 5

Describe the main features and gross appearance of an astrocytoma

Answer 5

• On cut surface, appear firmer than normal parenchyma, whitish and poorly to un-demarcated
• Increasing malignancy (cell atypia, infiltration, mitoses) -> neoangiogenesis (red colour) -> necrosis (malacia)
• Generally arise in the cerebral hemisphere white mater

Question 6

Describe the histological appearance of an astrocytoma

Answer 6

• Lots of astrocytes

- Immunohistochemistry shows lots of brown which represents astrocytes

Question 7

Which breeds have a strong susceptibility for oligodendroglioma?

Answer 7

Brachycephalic breeds

Question 8

Where do oligodendrogliomas mostly occur?

Answer 8

Frontal, temporal and parietal cortex

Question 9

Describe the gross features of a oligodendroglioma

Answer 9

• Well circumscribed, sharply demarcated, gelatinous (jelly)

- Areas of necrosis, haemorrhage and cystic degeneration are associated with increased malignancy

Question 10

Describe the histological features of a oligodendroglioma

Answer 10

Honeycomb appearance, small nuclei surrounded by empty halo (lipid dissolution during processing)

Question 11

Name the tumour arising from the meninges

Answer 11

Meningioma - most common CNS tumour

Question 12

Describe the gross features of a meningioma

Answer 12

Lobulated, often granular, white to tan with a broad based attachment to the meninges
- Preferentially located in the anterior fossa, more commonly over the cerebral convexities

Question 13

Describe the histological features of a meningioma

Answer 13

Whorls and streams of spindloid cells associated with moderate amount of vascular stroma.
Cells have undefined cell boundaries, moderate amount of basophilic cytoplasm and oval nucleus. Whorls are often centred on mineralized centres (psammoma bodies)

Question 14

What are the main features of a choroid plexus papilloma/carcinoma?

Answer 14

• Arising from epithelium of the choroid plexuses
• Mainly in the fourth ventricle
• Papilloma = benign, carcinoma = malignant

Question 15

Describe the gross appearance of a choroid plexus papilloma/carcinoma?

Answer 15

• Large, granular and rough texture
• In carcinomas, haemorrhages, necrosis and infiltration of the ventricular wall are observed between the cerebellum and the brainstem

Question 16

What are the main features of an ependymoma?

Answer 16

• Arising from ependyma lining the ventricles
• Frequently associated with obstructive hydrocephalus
• Metastases can occur (by CSF)

Question 17

Describe the gross appearance of an ependymoma

Answer 17

Large, well-demarcated, tan, solid intraventricular mass (granular texture)

Question 18

Describe the histological appearance of an ependymoma

Answer 18

Pseudorosettes - perivascular radial arrangement of neoplastic cells around a small blood vessel.

Question 19

How can a melanoma in the brain be differentiated from a haemangiosarcoma?

Answer 19

Melanoma: less demarcated, entirely flat
Haemangiosarcoma: well demarcated, very firm component, surrounded by fluid

Question 20

Describe the histological pattern seen for a haemangiosarcoma

Answer 20

• Cells are trying to remake the appearance of the bloodstream
• Heavy proliferation, mitosis
• No cells resemble epithelial cells and the ones present are all different from each other

Question 21

Describe the histological pattern seen for a melanoma

Answer 21

• Metastasis of a melanoma
• A lot of mitosis
• Some cells are producing melanin

Question 22

Provide a diagnosis for the following lesion: Spinal cord, Epidural space. Massive infiltration of an abundant population of neoplastic lymphocytes.

Answer 22

Lymphoma, spinal cord metastasis

Question 23

What is axonal degeneration (Wallerian degeneration)?

Answer 23

Segmental degeneration of axons and myelin caudally to the site of an insult

Question 24

How does axonal degeneration (Wallerian degeneration) appear histologically?

Answer 24

Formation of multiple spherical enlargements containing swollen axons (spheroids) -> disintegration of myelin -> necrosis -> infiltration of macrophages (digestion chambers) -> proliferation of Schwann cells (repair attempt) -> axonal sprouting (generation of multiple axonal sprouts)

Question 25

What does Wallerian-like mean?

Answer 25

Term used when the degeneration is not the consequence of focal trauma (ischemia)

Question 26

What are the consequences of lack of conduction due to axonal degeneration (Wallerian degeneration)

Answer 26

- Denervation atrophy of the effector organ (muscle, in particular) - Anterograde and retrograde transynaptic neuronal degeneration (chromatolysis)

Question 27

What are the features of Wallerian degeneration?

Answer 27

Segmental severe enlargement of the myelin sheath with disintegration of the axon and influx of macrophages (digestion chamber)

Question 28

Name a vascular disease of the PNS

Answer 28

Ileo-aortic thromboembolism

Question 29

Describe ileo-aortic thromboembolism

Answer 29

- Thrombosis of distal abdominal aorta at the junction with internal and external iliac arteries -> acute ischemic infarction of the peroneal and tibial nerves and muscles - Associated with valvular endocarditis (cause) and asymmetrical (or symmetrical) cyanoses of the plantar surface (cold and pale)

Question 30

How does ileo-aortic thromboembolism present clinically?

Answer 30

- Sudden (vascular!) paraparesis or paraplegia with painful hard muscle and lacking of femoral pulse - Common in cats

Question 31

Name the specific inflammatory term for the following anatomical locations: - Spinal ganglia - Spinal ganglia and related nerves - Nerves, both cranial and spinal

Answer 31

- Ganglionitis - Ganglineuritis - Neuritis

Question 32

Define neuropraxia trauma

Answer 32

The nerve is structurally intact. Mechanical contused traumas impaired temporarily the transmission of impulses. Full recovery will follow

Question 33

Define axonotmesis trauma

Answer 33

The axon is structurally damaged and interrupted. The basal lamina (endonevrium) is intact. The axon can regenerate in month or years, depending on the distance with the effector organ

Question 34

Define neurotmesis trauma

Answer 34

Entire nerve is truncated, and regeneration will be not effective.

Question 35

Describe compression of the caudal equina trauma

Answer 35

Associated with stenosis of the lumbosacral spinal canal. | Chronic axonal degeneration will follow

Question 36

What is dysautonomias?

Answer 36

Neuronal degeneration followed by reactive gliosis/satellitosis

Question 37

Compare acute and chronic dysautonomia

Answer 37

* Acute: dying within days | * Chronic: long lasting and with frequent remission

Question 38

Dysautonomia is associated with which animals?

Answer 38

Grazing animals (grass sickness)

Question 39

Which bacteria is related to Dysautonomia?

Answer 39

Clostridium botulinum type C

Question 40

How does Dysautonomia affect the GI tract?

Answer 40

- Relative diffuse shortening and blunting of the intestinal villi - Associated inflammation and superficial accumulation of mucous/haemorrhage and acute inflammation

Question 41

Describe the histological appearance of acute Dysautonomia

Answer 41

Plexuses contain an elevated number of neurons, many of which exhibit acute degenerative changes (e.g. chromatolysis)

Question 42

Describe the histological appearance of sub-acute Dysautonomia

Answer 42

Plexuses contain a reduced number of (degenerated) neurons in association with mild to moderate proliferation on non-neuronal elements

Question 43

Describe the histological appearance of chronic Dysautonomia

Answer 43

Plexuses are difficult to detect, cellularity is severely decreased and there is marked proliferation of non-neuronal elements

Question 44

Chromatolytic neurones indicate which types of Dysautonomia?

Answer 44

Acute to subacute

Question 45

A submucosal plexus indicates which type of Dysautonomia?

Answer 45

Chronic