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CNS > Pineal gland and germ cell tumours > Flashcards

Pineal gland and germ cell tumours Flashcards

1
Q

How common are pineal gland tumours?

A

Adult: 1% of brain tumours
- 30-40% germinoma
- 20% NGGCT

Children: 5% of brain tumour
- 50% germinoma
-30% pineal parenchyma tumour

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2
Q

What types of pineal parenchyma tumours are there?

A

Pineocytoma (Gr 1-2)

Pineal parenchyma tumour of indeterminate differentiation (PPTID)
Grade 2-3

Pineoblastoma Gr 4

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3
Q

How common is pineoblastoma?

A

Second most common type of pineal gland tumour after Germ cell tumour

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4
Q

Microscopic features of Pineocytoma

A

Uniform, small mature cells (resembling normal pineal cells) that grow primarily in sheets and often form large pineocytomatous rosettes

Round nuclei with fine chromatin
Lots of processes

No Mitotic activity
Ki67 <1%

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5
Q

What age group does Pineocytoma usually occur in?

A

Adults

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6
Q

Microscopic features of Pineal parenchyma tumour of intermediate differentiation (PPTID)

A

Diffuse sheet or large lobules of monomorphic round cells that appear more differentiated than in pineoblastoma.

Pleomorphic cells may be present

Mitotic activity low-moderate
Ki67 often >5%

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7
Q

Microscopic features of Pineoblastoma

A
  • Resembles other primitive neuroectodermal tumours e.g medulloblastoma
  • patternless sheets of small immature neuro-epithelial cells
  • High N:C ratio
  • Hyperchromatic
  • Frequent mitoses
  • Homer-wright rosettes
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8
Q

What is the natural hx of pienoblastoma

A

More common in children <5years

Aggressive

Invades nearby structures and spreads via CSF

High risk of craniospinal dissemination -50%

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9
Q

Treatment paradigm for pineocytoma

A

Treat like LG Glioma
Maximal safe resection

GTR —> observation
STR —> post op RT can be considered or observation with RT at time of progression (50-54Gy)

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10
Q

Treatment paradigm for Pineoblastoma

A

Treat like medulloblastoma

Maximal safe resection —> CSI 23.4-36Gy in 13-20# + tumour bed boost to 50.4Gy if <3yo or 54Gy if >3yo

CHT prior to CSI for young children or those with STR to try improve resection with a second look surgery

Enrolment on high risk MB COG trials

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11
Q

Epidemiology of germ cell tumour

A

-Peak age 10-12yo, majority <20yrs
- Rare in early childhood
- Younger tend to have NGGCT, older tend to have pure germinoma
- 3% of childhood CNS malignancies

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12
Q

Anatomy relating to intracranial germ cell tumours

A

Usually arise from the proximal 3rd ventricle and affect supratentorial midline structures e.g. pineal gland, hypothalamus, basal ganglions

Subependymal spread occurs near 3rd and 4th ventricle

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13
Q

What are the classifications of germ cell tumours

A

WHO classifies them as Pure Germinoma 2/3 vs non germinomatous germ cell tumour (NGGCT) 1/3

NGGCT further divided into:
- embryonal carcinoma
- endodermal sinus/yolk sac tumour
- choriocarcinoma
- teratoma
- mixed tumours

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14
Q

Prognosis of intracranial germ cell tumours

A

Pure germinomas:
Very favourable, 5year OS 95%
treatment sensitive, require less intense therapy

NGGCT:
More aggressive than Pure germinoma
Require multimodality treatment
5 year OS 90%

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15
Q

Why is surgery not used in intracranial germ cell tumour?

A

Surgery is often restricted to biopsy only as the morbidity and mortality of resection can near 20%

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16
Q

Treatment of non metastatic pure germinoma?

A

Induction chemo –> Whole ventricular irradiation + boost RT (NO CSI)

CHCT with 4 cycles carboplatin/etoposide –> 18-24Gy Whole ventricular irradiation with 12Gy/8# boost to suprasellar GTV

(if CR to chemo 18Gy WVI, if PR 24Gy)
(per ACNS1123)

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17
Q

What is the significance of whole ventricular irradiation in germ cell tumours?

A

Due to natural hx of germ cell tumours to have subependymal spread, along ventricular lining that may not be visible on MRI.

In prior studies of involved field RT alone, over 80% of failures were located in the periventricular region, supporting WVI as standard.

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18
Q

What is the treatment of metastatic (CSF+) germinoma?

A

Induction chemo –> WVI + boost RT + CSI

CHT with 4 cycles of carboplatin/etoposide –> WVI 18-24Gy + Supra seller GTV boost to 45Gy + CSI 24Gy/16#

(so same as non metastatic but with CSI and higher boost dose. fractionation is still 1.5Gy/#)

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19
Q

What dose per fraction is used in germinoma?

A

1.5#

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20
Q

Treatment of localised NGGCT

A

Induction chemo –> WVI/CSI + boost RT
(note- doses higher compared to germinoma)

Chemo 6x carbo/etoposide alternating ifos etop, then CSI to 36Gy with Suprasellar GTV boosted with 18GY/10# to 54Gy/30# (total dose)

21
Q

What did the ACNS1123 show for NGGCT

A

Ommission of CSI in patients who responded to chemo and had WVI instead for NGGCT led to high rates of spinal failure

22
Q

Treatment of metastatic NGGCT

A

Induction chemo –> CSI + boost RT

Chemotherapy 6 x carbo/etop, alt ifosfamide/etop; –>
CSI 36GY/20# + 18Gy/10# boost to GTV (total dose 54Gy/30#) + 9Gy/5# to bulky spinal mets (total dose of 45Gy/25#)

23
Q

How might a tumour in the pineal region present?

A

Obstructive hydrocephalus due to compression of 3rd Ventricle

Increased ICP- headache, nausea+vomiting, papilloma, lethargy

Ataxia

Seizure

Behaviour changes

Parinaud syndrome-poor upward gaze, accomodation but abnormal light response due to pressure on superior colliculus

24
Q

How might a supra sella tumour present?

A

Hypothalamic/pituitary dysfunction

  • Diabetes insipidus due to reduced ADH
  • Growth hormone abnormalities: delayed or precocious puberty
  • Isolated GH deficiency
  • Hypothyroidism
  • Adrenal insufficiency

Ophthalmologic abnormalities
- usually bitemporal hemianopia

Classic triad: Diabetes insidious + precocious puberty + visual deficit.

25
Q

Work up- examination

A

Neurological exam
Baseline Ophthal assessment

26
Q

Work up- blood tests and CSF

A

Bloods:
- B-HCG
- AFP

CSF:
- cytology
-AFP
- B-HCG
- PLAP (placental alkaline phosphatase)
- c-Kit

27
Q

Work up- tissue diagnosis

A

Standard of care is tissue diagnosis obtained surgically if this is safe.

ACNS 1123 study allowed treatment stratification based on CSF and serum markers of AFP and B-HCG

If serum/CSF AFP and B HCG normal then biopsy done to distinguish pure germinoma from other tumour

28
Q

Describe volumes for treatment of germ cell tumour

A

CTV (boost): pre chemo GTV on MRI + 1cm expansion

CTV (WVI): CTV (boost) + whole ventricle including lateral, 3rd and 4th Vent.) and supra seller cistern + pineal cistern + pre-pontine cistern + 1cm expansion

PTV: CTV + 3mm expansion

29
Q

Microscopic features of Germinoma

A

Large polygonal cells with clear to eosinophilic cytoplasm,
distinct cell membranes,
vesicular chromatin,
prominent nucleoli
Fibrous septae and nested architecture
Lymphocytic infiltrate

30
Q

Microscopic features of Yolk sac tumour

A

Many patterns/architecture
Often hypo cellular myxoid areas
Most common = reticular/microcystic

Classic: Schiller-Duval bodies, Hyaline globules, variable architecture

Elevated serum AFP

31
Q

Microscopic features of embryonal carcinoma

A

Large primitive cells
Vesicular nuclei with prominent nucleoli
Variable architecture (nests, sheets, glands)

32
Q

Microscopic features of Choriocarcinoma

A

Malignant cytotrophoblasts (mononuclear) and synctiotrophoblasts (multinucleate)

Abundant haemorrhage

Elevated serum/CSF hCG

33
Q

Microscopic features of teratoma

A

Composed of tissues from 2-3 germ layers
Common elements are skin (with adnexal structures), cartilage, GI, Brain etc

Mature has adult type tissues
Immature has fatal/embryonic tissue

34
Q

IHC Choriocarcinoma

A

Glypican 3

35
Q

IHC yolk sac tumour

A

SALL4
CD30
Glypican 3

36
Q

IHC Embryonal carcinoma

A

SALL4
OCT 3/4
D2-40
CD30

CD117 -

37
Q

IHC seminoma/germinoma

A

SALL4 +
OCT 3/4 +
D2-40 +
CD117 +

CD30 -
Glypican 3 -

38
Q

What proportion of germ cell tumours present with metastatic disease in the neuro axis at diagnosis?

A

5-10%

39
Q

Work up- imaging

A

Contrast enhanced MRI of brain and whole spine

40
Q

What is the serum marker pattern seen in germinoma?

A

AFP normal
BHCG usually low (if increased is poor prognostic factor
C-Kit +
PLAP +

41
Q

What serum markers are usually raised in NGGCT

A

AFP and BHCG

42
Q

Where do the majority of intracranial germ cell tumours arise?

A

Midline proximal 3rd ventricular structures:

2/3 pineal
1/3 suprasellar

Other sites include basal ganglia, thalamus, cerebral hemispheres

5-10% present with both pineal and suprasella tumours, these tend to be bifocal rather than metastatic

43
Q

What is the ddx for a paediatric brain tumour in the pineal region?

A

Pineoblastoma
Pineocytoma
PPT of intermediate differentiation
Germinoma
NGGCT
Glioma
Meningioma
Lymphoma
Benign cyst
Langerhans cell histiocytosis
harmatoma

44
Q

What is the ddx for a paediatric brain tumour in the suprasellar region?

A

Germinoma
NGGCT
craniopharyngioma
Pituitary adenoma
meningioma
glioma
aneurysm
infection
Metastatic disease

45
Q

Historically, how was RT used in the dx of intracranial germinomas?

A

Tumours were irradiated with a test dose of 10-20Gy.
If there was a response, the dx was germinoma, and RT was continued to a definitive dose of 40-56Gy.

This is no longer done

46
Q

For which pineal tumour is surgery generally not done?

A

Not done for germinomas as they are radiosensitive tumours and surgery can lead to morbidity

47
Q

What hypothesis was tested in the ACNS1123 study?

A

If neoadj chemo can help reduce RT doses and volumes in localised germinoma and NGGCT

48
Q
A

CNS (9 decks)

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