Pineal region tumours

Question 1

What are the 3 commonest tumours found in the pineal region?

Answer 1

1. Germ cell tumours (germinomas, teratomas);
2. Astrocytomas;
3. Pineal tumours (mostly pineoblastomas).

Question 2

What 2 CSF markers are useful for following tumour response to treatment?

Answer 2

1. AFP (alpha fetoprotein);

2. β-HCG (beta-human chorionic gonadotropin).

Question 3

Why are CSF markers less useful for diagnosis and more useful for monitoring response to treatment?

Answer 3

Pineal region tumours may be of mixed cell types, hence markers are less useful as a diagnostic tool.

Question 4

What are the anatomical boundaries of the pineal region?

Answer 4

1. Dorsally: splenium of corpus callosum and the tela choroidea;
2. Ventrally: quadrigeminal plate and midbrain tectum;
3. Rostrally: posterior part of third ventricle;
4. Caudally: cerebellar vermis.

Question 5

What are the 5 features of Parinaud’s syndrome?

Answer 5

1. Supranuclear upgaze palsy;
2. Lid retraction (Collier’s sign);
3. Convergence palsy;
4. Accommodation palsy;
5. Others: pseudoabducens palsy; see-saw nystagmus; fixed pupils; dissociated light-near response; internuclear ophthalmoplegia…

Question 6

What is the natural history of pineal cysts?

Answer 6

Probably nonneoplastic, however not completely known with certainty.

Question 7

What symptoms may result from an enlarging pineal cyst?

Answer 7

1. Obstructive hydrocephalus;
2. Gaze paresis (including Parinaud’s syndrome);
3. Hypothalamic symptoms.

Question 8

Which pineal region neoplasms metastasise easily via the CSF?

Answer 8

1. Germ cell tumours;
2. Ependymomas;
3. Pineal cell tumours.

Question 9

What are the features of pineocytomas?

Answer 9

1. Well differentiated;
2. Arise from pineal epithelium;
3. Metastasize through CSF;
4. Radiosensitive.

Question 10

What are the features of pineoblastomas?

Answer 10

1. Malignant tumour (PNET);
2. Metastasize through CSF;
3. Radiosensitive.

Question 11

Where in the CNS do germ cell tumours arise?

Answer 11

In the midline, either suprasellar or pineal region, or both (synchronous germ cell tumours).

Question 12

Are germ cell tumours radiosensitive?

Answer 12

Yes, highly sensitive.

Question 13

What are the types of germ cell tumour?

Answer 13

1. Germinomas;

2. Non-germinomatous germ cell tumours.

Question 14

What are the features of germinomas?

Answer 14

1. Malignant tumours of primitive germ cells;
2. Occur in the gonads or the CNS;
3. Survival is better than non-germinomatous tumours.

Question 15

What tumours make up the non-germinomatous germ cell tumour group?

Answer 15

1. Embryonal carcinoma;
2. Choriocarcinoma;
3. Endodermal sinus tumour (yolk sac carcinoma);
4. Teratoma (mature or immature).

Question 16

What are the commonest pineal region tumours in children and young adults?

Answer 16

1. Germ cell tumours;

2. Pineal cell tumours.

Question 17

What are the commonest pineal region tumours over the age of 40?

Answer 17

1. Meningioma;

2. Glioma.

Question 18

What are the presenting features of pineal region tumours?

Answer 18

1. Hydrocephalus;
2. Seizures;
3. Parinaud’s syndrome (or the syndrome of the sylvian aqueduct);
4. Precocious puberty, only in boys with β-HCG secreted in the CSF (has leuteinizing hormone like effects);
5. Radiculopathy or myelopathy from drop metastases.

Question 19

What is “test dose” radiation?

Answer 19

The now-outdated practice of giving a test dose of 5 Gy in an attempt to shrink a pineal region tumour, “proving” its diagnosis as germinoma despite no pathological specimen obtained.

Question 20

What is an accepted management plan for pineal region tumours?

Answer 20

1. MRI or brain and spine for drop mets;
2. Test for germ cell tumour markers in serum, and CSF if able;
3. Tissue diagnosis: generous biopsy to avoid missing multiple histologies in mixed cell tumours; transventricular if hydrocephalus, open biopsy or stereotactic if no hydrocephalus;
4. Depending of markers and histology: chemotherapy and XRT for germinomas; resection and adjuvant XRT vs XRT alone for all other tumours.

Question 21

What percentage of patients with pineal germ cell tumours and hydrocephalus will require permanent CSF diversion?

Answer 21

90%.

Question 22

What is the complication rate of stereotactic biopsy for pineal region tumours?

Answer 22

1. Mortality: 1.3%.
2. Morbidity: 7%;
3. Fail to achieve histological diagnosis: 6%.

Question 23

What are the indications for surgical resection of pineal region tumours? N.B.: controversial.

Answer 23

1. Radioresistant tumours (eg malignant nongerminomatous) WITHOUT evidence of metastasis;
2. Benign tumours (eg meningioma, teratoma);
3. Well encapsulated tumours;
4. Pineocytoma (with SRS for residual disease).

Question 24

What surgical approaches are available for pineal region tumours?

Answer 24

1. Midline infratentorial supracerebellar (avoid if tentorial angle is too steep);
2. Occipital transtentorial;
3. Transventricular;
4. Lateral paramedian infratentorial;
5. Transcallosal (only for tumours extending into corpus callosum);
6. Paramedian infratentorial supracerebellar.

Question 25

What is the surgical outcome after resecting pineal region tumours?

Answer 25

1. Mortality: 5-10%;

2. Complications: visual field deficit; cerebellar ataxia.