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FRCS Part 1 > CH37 & 38 Other gliomas, ependymal, choroid plexus and neuronal tumours > Flashcards

CH37 & 38 Other gliomas, ependymal, choroid plexus and neuronal tumours Flashcards

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1
Q

Commonest glioma in paediatric patients?

A

Pilocytic astrocytoma

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2
Q

What is the commonest genetic abnormality in pilocytic astrocytomas?

A

BRAF mutation (which activates MAPK pathway) 15-20% of NF1 patients also have pilocytics (more commonly optic gliomas)

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3
Q

What are the histological appearance of pilocytic astrocytomas?

A

2 main cell populations; 1) cells with long thin bipolar processes (resembling hairs—hence pilocytic) with Rosenthal fibers. 2) loosely knit tissue comprising stellate astrocytes with microcysts and occasional eosinophilic granular bodies. Histology alone may be inadequate for diagnosis.

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4
Q

What is the radiological appearance of a pilocytic astrocytoma?

A

66% have an enhancing nodule with a cyst. Can also be necrotic centre or no cyst at all.

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5
Q

When would you give radiotherapy to a pilocytic astrocytoma?

A

Only for recurrence with malignant histology or if recurrence is non-resectable (surgery is preferred treatment)

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6
Q

What is the diencephalic syndrome?

A

A rare syndrome seen in paeds, usually caused by infiltrating glioma into the anterior hypothalamus:

Cachexia/Failure to thrive

Hyperactivity

Euphoric affect

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7
Q

When do you operate on brainstem gliomas?

A

Hydrocephalus (shunt)

Dorsally exophytic tumours as these are generally benign (e.g. ganglioglomas and amenable to radical subtotal resection)

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8
Q

What feature makes a pleomorphic xanthoastrocytoma go from grade 2 to 3 (anaplastic)

A

>5 mitotic figures on high power field or necrosis

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9
Q

Where do myxopapillary ependymomas occur, what grade are they?

A

Filum terminale, WHO grade 1

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10
Q

Where is the most likely location for an adult ependymoma?

A

Intramedullary, arising from the central canal of the spinal cord. Histologically they are thought to arise from radial glial cells.

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11
Q

Where do ependymomas occur in children (most commonly)?

A

Posterior fossa

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12
Q

What post-op investigation must be done following resection of an ependymoma specifically?

A

LP for cytology to check for drop mets ~2 weeks post-op. This is prognostic!

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13
Q

How do you differentiate radiologically between ependymoma and medulloblastoma?

A

4th ventricle drapes around medulloblastoma ( “banana sign”) from the anterior aspect, c.f. ependymoma which tends to grow into 4th ventricle from the floor. Ependymoma may grow through foramen of Luschka and/or Magendie (plastic). Ependymomas tend to be inhomogeneous on T1WI MRI (unlike MB) the exophytic component of ependymomas tends to be high signal on T2WI MRI (with MB this is only mildly hyperintense) calcifications: common in ependymomas, but only in < 10% of MB

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14
Q

Would you give radiotherapy to a completely resected ependymoma?

A

Yes. Significant improvement in survival adjuvant radiotherapy to surgical bed. (recent recommendation for 59.4Gy +1cm margin)

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15
Q

How would a positive LP for cytology in ependymoma change the management plan?

A

Likely to give whole spine radiotherapy

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16
Q

Which type of ependymoma is most common in the spinal cord?

A

Tanycytic ependymoma

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17
Q

What grade is a myxopapillary ependymoma?

A

Grade 1 filum terminale tumour All other ependymomas grade 2 or 3

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18
Q

What are the different grades of choroid plexus tumours?

A

Grade 1 - Choroid plexus papilloma

Grade 2 - Atypical CPP

Grade 3 - Choroid plexus carcinoma

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19
Q

What is the gene associated with choroid plexus papilloma?

A

Gene for potassium channel KIR7.1

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20
Q

Where do choroid plexus papillomas tend to occur in children?

A

Supratentorial, lateral ventricle, more so on left. In adults more likely to occur infratentorial

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21
Q

How do you differentiate between grade 1 and 2 choroid plexus papilloma?

A

More mitotic figures (≥ 2 mitoses per 10 randomly selected HPFs) without frank signs of malignancy seen in choroid plexus carcinoma up to 2 of the following 4 features may be observed: increased cellularity, nuclear pleomorphism, blurring of the papillary pattern (solid growth) and areas of necrosis. They are more likely to recur than their grade I counterparts.

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22
Q

What are the histological features of a choroid plexus carcinoma?

A

Choroid plexus carcinoma (CPC) show at least 4 of the 5 following features: 1. frequent mitoses: usually > 5 mitoses per 10 HPF 2. increased cellular density 3. nuclear pleomorphism 4. blurring of the papillary pattern with poorly structured sheets of tumor cells 5. necrosis

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23
Q

What grade is a DNET?

A

WHO grade 1

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24
Q

What are the most common locations for pilocytic astrocytomas?

A

Cerebellar hemisphere

Optic nerve

Hypothalamus

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25
What is the principle CNS tumour associated with NF1?
Pilocytic astrocytoma
26
What condition is associated with OPGs?
NF1
27
What % of NF1 patients develop a pilocytic astrocytoma?
20%
28
29
What is the surgical goal in pilocytic astrocytoma?
Resection of the solid nodule component only. Removal fo the cyst wall is not necessary.
30
What are the imaging features of an OPG?
Uniform dilation of the optic nerve extending \>1 cm in length.
31
How would you approach an OPG surgically?
Single optic nerve involvement causing proptosis and visual loss should be managed transcranially with resection from the back of the globe to the chiasm. This causes a junctional scotoma = monocular visual loss + superior temporal quadrantanopia in the contralateral eye due to damage to the knee of wilbrand.
32
What adjuvent treatment do you given for OPGs?
Chemotherapy. Radiotherapy is avoided unless there is tumour post-op/recurrence or if it is malignant
33
How do hypothalamic gliomas present?
Diencephalic syndrome (cachexia, hyperactivity and euphoric affect) Endocrine disturbances (hypoglycaemia, DI and precocious puberty) Hydrocephalus (headache, nausea/vomiting and macrocephaly)
34
How do brainstem gliomas present?
Upper = cerebellar symptoms (ataxia / gait disturbance) and hydrocephalus Lower = multiple cranial nerve deficits (diplopia / facial weakness / bulbar signs) and long tract findings (weakness)
35
What are the growth patterns of brainstem gliomas?
Diffuse Cervicomedullary Focal Dorsally exophytic
36
How do you treat brainstem gliomas?
Surgery if dorsally exophytic Temozolomide may help in paeds Radiotherapy and steroids Most die within 6-12 monmths of diagnosis
37
What are the clinical features of a tectal glioma?
Diplopia Visual field defect Nystagmus Parinaud's syndrome Ataxia Seizures Hydrocephalus
38
What are tectal gliomas histologically?
Pilocytic astrocytomas Diffuse astrocytomas Ependymomas Oligodendrogliomas
39
What are the treatment options for tectal gliomas?
VP shunt or ETV (allows biopsy if needed) SRS if tumour progression (20%)
40
What are pilomyxoid astrocytomas?
Variants of pilocytic astrocytomas. These have no WHO grade. They are more aggressive, more likely to recur and spread in the CSF. Histologically does not contain rosenthal fibres or eosinophilic granular bodies.
41
What are Rosenthal fibres?
Eosinophilic cytoplasmic inclusions
42
What is the typical location of a SEGA?
Arises from the lateral wall of the ventricle adjacent to the foramen of monroe
43
What are the important features of PXAs?
WHO grade 2 Superficial location (thought to arise from subpial astrocytes) \>90% are supratentorial Mural nodule with cyst in 25% Involve the meninges in 2/3 of cases Well circumscribed and lipid laden
44
What genetic mutation is common with PXA?
BRAF V600E IDH-mutant
45
What is the mainstay of treatment for PXAs?
Gross total resection - 5 y survival 80% No role for radiotherapy or chemotherapy
46
What are the key features of subependymomas?
WHO grade 1 Arise from the ependyma protruding into the ventricle Mostly incidental and do not need intervention, rarely cause hydrocephalus. Unlike ependymomas, these are NON-enhancing
47
Is there are link between progression free survival and WHO grading of ependymoma?
Nope
48
What are the histological findings with an ependymoma?
Often fibrillary with epithelial appearances. Perivascular pseudorosettes or true rosettes are seen with the papillary form.
49
What is the most common location presentation of a 4th ventricular ependymoma?
Obstructive hydrocephalus and CN 6 & 7 palsy
50
What are the main differential diagnoses of a posterior fossa mass in a child?
Pilocytic astrocytoma (35%) Medulloblastoma (30%) Ependymoma (10%) Haemangioblastoma (2%)
51
Why do you get CN6 and 7 palsies with posterior fossa tumours?
As they compress the facial colliculus in the floor of the 4th ventricle which compresses the CN6 nucleus and the CN7 axons.
52
What structure lies beneath the striae medullaris in the floor of the 4th ventricle?
The facial nerve fibres as they run from the facial nucleus laterally to war around the the abducent nucleus medially. The lower part of the striae medullaris covers the vestibulocochlear fibres.
53
Why is it difficult to get a complete resection with post-fossa ependymomas?
As they tend to invade the obex making complete resection impossible. This results in a worse prognosis.
54
Where do ependymomas arise from?
The floor of the 4th ventricle (compared to medulloblastomas that arise from the roof!)
55
What cardiac side-effect may occur with ependymomas that extend through foramen of luschka?
Bradycardia
56
What adjuvent therapy is following resection of ependymomas?
Radiotherapy. This improved median survival time by 2 years.(not given if \<3 years old). No role for chemotherapy
57
What are the main morbidities with operating on 4th ventricular ependymomas?
Need for NG tube and tracheostomy due to involvement of the floor of the 4th.
58
What are the histological subtypes of ependymoma?
WHO grade 1 = Subependymoma / myxopapillary ependymoma WHO grade 2 = Papillary, clear cell, tanycytic and RELA fusion positive
59
Which tumour types are composed of papillae histologically?
Choroid plexus papillomas (have a basement membrane) and papillary ependymomas (no basement membrane)
60
Which ependymoma subtypes can be mistaken histologically for gliomas?
Clear cell can be mistaken for oligodendrogliomas Tanycytic can be mistaken for pilocytic astrocytomas
61
Which ependymoma subtype has the worse prognosis?
RELA-fusion positive (WHO grade 2-3). Present in 70% of supratentorial ependymomas and almost none of the infratentorial.
62
Which type of glioma classically arises from the hypothalamus and protrudes into the 3rd ventricle?
Chordoid glioma of the 3rd ventricle (WHO 2)
63
What are the most common locations for CPPs?
Lateral ventricle, 4th ventricle and CPA. Note mostly infratentorial in adults and supratentorial with a predilection for the left side in paeds.
64
What are the histological findings in CPP?
Normal choroid plexus with little or no mitotic activity. Most cells are + for the gene that encodes the potassium channel KIR7.1 protein.
65
What proportion of choroid plexus papillomas arise below the age of 2 years?
70%
66
Why do subdural collections occur following resection of choroid plexus papillomas?
Due to persistent ventriculosubdural fistulas that may require shunting
67
What are the imaging features of a DNET?
Hypo T1, Hyper T2, partial FLAIR suppression & no contrast enhancement.
68
What are the imaging features of a ganglioglioma?
Gangliogliomas (WHO grade 1) Iso T1 with bright contrast enhancement, and Iso/hyper T2. Due to calcification may show blooming on GRE
69
What are the histological features of gangliogliomas?
Contain neoplastic cells of neuronal and glial components.
70
What is the treatment for gangliogliomas?
Complete surgical resection
71
What is Lhermitte Duclos disease?
Dysplastic cerebellar gangliocytoma = hamartoma of the cerebellum (strongly associated with Cowden syndrome)
72
What grade are central neurocytomas?
WHO grade 2
73
Where are central neurocytomas attached to?
The septum pellucidum.
74
What is the management of central neurocytomas?
Gross total resection. If Ki-67 is elevated then radiotherapy after subtotal resection may reduce recurrence.
75
What are the histological features of a central neurocytoma?
Similar to oligos with a fried egg appearance on H&E staining. Staining is positive for synaptophysin and Neu-N showing neuronal lineage compared to oligos which are GFAP positive. There is also no 1p19q mutation.
76
What is a cerebellar liponeurocytoma?
WHO grade 2 lesion that occurs in the cerebellum of adults with neuroplastic neurocytes that resemble adipocytes.
77
What are paragangliomas?
Aka glomus tumours / phaeochromocytomas. These are WHO grade 1 neuroendocrine tumours that arise from neural crest cells. These occur in the filum terminale or the jugular foramen.
78
What do glomus tumours secrete?
Adrenaline and noradrenaline which may cause life-threatening hypertension and arrhythmias.
79
What condition are phaeochromocytomas associated with?
VHL, MEN2a/2b and NF1
80
Which patients with phaeochromocytomas should undergo genetic testing?
If \<50 years at the time of diagnosis
81
What lab investigations should be performed in patients with suspected phaeochromocytomas?
Plasma fractionated meta-nephrines (replaces VMAs). Urine total catecholamines and meta-nephrines. If raised then a clonidine suppression test can be done which should cause a fall \<50% in normal cases but will not change with phaeos!
82
What is this?
Carotid body tumour (aka chemodectoma)
83
What is the term given to a glomus tumour with middle ear invasion?
Glomus tympanicum
84
What is carcinoid/seratonin syndrome?
Bronchoconstriction, abdominal pain, diarrhoea, headache, flushing, hypertension and hyperglycaemia. Occurs with glomus tumours due to seratonin release.
85
What grading system is used for glomus tumours?
Modified Jackson classification: 1 - Small, limited to jugular bulb, middle ear and mastoid 2 - Extends under the IAC 3 - Extends to petrous apex 4 - Extends into clivus / infratemporal fossa
86
What pre-op meds should be given before GA in glomus tumours?
Alpha blocker - Phenoxybenzamine to prevent periph vasoconstriction. Beta blocker - Propanolol
87
What is the treatment for glomus tumours?
Surgical resection through the neck +/- pre-op embolisation. Often the IJV is sacrificed. Radiation / SRS if surgery not possible.

FRCS Part 1 (85 decks)

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