APATH - Tumours

Question 1

List three (3) different types of brain herniation (1½)

Answer 1

Subfalcine (cingulate), transtentorial (uncinate, mesial temporal), tonsillar herniation

Question 2

Outline the main mechanism of death in cerebral herniation (1½)

Answer 2

Compression of cardiac and respiratory centres in the medulla oblongata

Question 3

Describe the features of a CAT scan or/special investigations that would lead you to suggest a patient is suffering from a metastasis to the brain (6½)

Answer 3

Primary tumour elsewhere: lung, colon, breast, renal, chorio

Multiple sites

Region of MCA territory [straightest course]

Located at grey/white matter interface

Ring enhancing lesion: indicate its components
o Marked surrounding oedema [dark]
o Circular area of contrast uptake [white]
o Central necrosis [dark]

Question 4

A patient with a metastatic carcinoma to the brain develops a neurological lesion as a result. Describe where this metastatic focus might/tend to be found, and briefly explain why (4)

Answer 4

Middle cerebral artery territory [straightest course into brain

Grey-white matter junction [acute branching of vessels at this site]

Question 5

List three (3) tumours which commonly develop metastases to the brain (1½)

Answer 5

Lung, breast, colon, melanoma, choriocarcinoma

Question 6

Use the following table to create a list of differential diagnoses for an acquired cerebral space occupying lesion (5½)

Inflammatory Infective
Inflammatory Non-infective
Neoplastic primary
Neoplastic secondary
Traumatic
Vascular

Answer 6

Two examples: Abscess, Tuberculosis, Toxoplasmosis, Hydatid disease

One example: Demyelinating pseudotumour

Two examples: Meningioma, glial and neuronal neoplasms, poorly-differentiated CNS neoplasms e.g. Medulloblastoma, primary CNS lymphoma, germ cell tumours

Two examples: Carcinoma, melanoma, lymphoma, sarcoma

Two examples: Extradural, subdural haematoma

Two examples: Intracerebral haemorrhage, aneurysm

Question 7

If a metastasis is indeed the correct diagnosis for Ms Malala, what would you expect the macroscopic appearance of the cut brain to be, and explain why this is so (3)

Answer 7

• Multiple haemorrhagic/necrotic parenchymal metastases
• Predominantly in the MCA territory at grey/white junction
• Choriocarcinoma is angioinavsive
• Measure progesterone at day 21 (mid luteal phase). A high value confirms ovulation.

Question 8

With the aid of a clear diagram, show how…

• a contralateral lesion can cause the symptom of R-sided motor weakness (i.e. L- sided lesion causing R-sided weakness) (2)
• an IPSILATERAL lesion can, in the face of raised intracranial pressure, cause the symptom of Right sided motor weakness (i.e. Right sided lesion causing Right sided weakness), indicating the tracts involved (5)

Answer 8

L-sided lesion involving motor cortex of R-side. Diagram must show decussation and crossing over to explain laterality.

R sided supratentorial lesion  R sided transtentorial herniation of parahippocampal gyrus [usually ipsilateral] [1]  pressure on brain stem with shift to L [1]. Outer edge of pons is compressed against the free edge of the tent on the L side [Kernohan’s notch] [1]. This carries long motor tracts from the R [1]. Decussation is at a lower level so the weakness is on the R side [false localizing sign] [1]

Question 9

The CAT scan also shows the presence of an additional lesion. A ring enhancing lesion is present in the L middle cerebral artery territory. The Chest X-Ray reveals a large lung mass which on Fine Needle Aspiration Biopsy is a moderately differentiated squamous cell carcinoma. It is presumed the ring enhancing lesion is due to a metastatic squamous cell carcinoma.

Describe the components seen in the ring enhancing lesion, and explain how they are pathophysiologically brought about by a metastatic carcinoma (3)

Answer 9

• Central black: Necrosis [Ca outgrows blood supply]
• White ring: Leaking vessels, ruptured by Ca. Leaks contrast media
• Black outer ring: Oedema fluid [vasogenic oedema]

Question 10

Diagnosis of squamous cell carcinoma of the lung. Clubbing and lung signs and symptoms, also complains of weakness in the Right arm and leg. O/E there is reduced power in these regions. He is sent for a CAT scan, on the assumption that there may be a Left sided metastatic lesion to the brain. The results, however, show the presence of a right sided lesion in the inferior cerebral cortex.

With the aid of two diagrams each showing the brain and upper spinal tracts, demonstrate how:
[i] a Left sided metastasis or [ii] a Right sided metastasis can produce the clinical weakness in this patient (8)

Answer 10

Diagram should show
i] cerebral cortex, tentorium cerebelli, parahippocampal gyrus, decussation
A. : L sided lesion with tracts through the decussation  R weakness
B. : R sided lesion [low in Prahippocampal area preferably]  R transtentorial herniation  compression of L side of brain stem against free edge of tent, compressing motor fibres from LEFT side  through decussation  R sided weakness

Question 11

State what should be looked for in the examination of the eyes of this patient to persuade one a space occupying lesion in the brain is present and explain anatomically how these lesions are brought about [for section B of the question, you do not need to justify laterality in the eye lesions] (6)

Answer 11

Papilloedema: CSF cuff round 2 nd cranial nerve (2)

Dilated pupil: Parasympathetic fibres compressed in 3 rd cranial nerve (2)

Drooping upper lid: Sympathetic / damage to 3 rd cranial nerve (2)