Ch 39 Pineal region tumours Flashcards
What is the commonest pineal region tumour?
Germinoma
What are the anatomical borders of the pineal region?
Superior - splenium of CC and tela choroidea
Inferior - quadrigeminal plate and tectum
Anterior - Back of 3rd ventricle
Posterior - internal cerebral veins and cerebellar vermis
Laterally - pulvinar of the thalamus
What is the commonest pineal region tumour over the age of 40?
meningioma or glioma
How do pineal region germinomas present?
Hydrocephalus
Perinauds syndrome (convergence-retraction nystagmus, up-gaze palsy and pseudo-argyll robertson pupil = near-light dissociation of the pupillary response)
Precocious puberty (in boys)
What are the histological findings of a pineocytoma?
pineocytomatous rosettes of uniform cells and/or pleomorphic cells having gangliocytic differentiation.
Label the structures in the pineal region
Splenium
Telechoroidae
Posterior commissure
Habenula commisure
Tectum
Internal cerebral vein > vein of galen
Name the veins from lateral to medial in the supracerebellar infratentorial approach.
Basal vein of rosenthal (lateral), internal cerebral veins and superior vermian vein
How are the veins displaced with meningiomas in the pineal region?
Inferiorly (whilst pineal tumours displace them upwards!). This should be considered with planning the approach as inferiorly displaced veins will make a supracerebellar infratentorial approach difficult.
How do you classify the differential diagnoses for pineal region tumours?
By the tissue of origin:
Pineal (pineocytoma, pineoblastoma, pineal tumour of intermediate differentiation and papillary pineal tumours)
Germ cells (germinoma, embryonal carcinoma, teratoma, mixed, yolk sac, choriocarcinomas, teratoma with malignant differentiation - mnemonic = GETMYCT)
Glial (astro/oligo)
Arachnoid (meningiomas / arachnoid cyst)
Ependyma (ependymoma)
Haematogenous (metastases)
Vascular (vein of galen / AVM /lymphoma)
Ectoderm (dermoid / epidermoid)
Infection (cysticercosis)
Which pineal region tumours cause drop mets?
GCTs, ependymomas and pineoblastomas
What is syndrome of the sylvian aqueduct?
Parinaud’s syndrome with additional down-gaze palsy
Why do pineal region tumour patients look like they have sunsetting?
Combination of lid retraction (Collier’s sign) and the upgaze palsy)
Why do germ cell tumours cause precocious puberty in boys?
Choriocarciomas and germinomas may cause LH release
What is suggested by the triad: DI, VFD and panhypopituitarism?
Suprasellar GCT
How do you manage a patient with a pineal region mass?
MRI whole neuroaxis with contrast (rule out drop mets)
Send serum and CSF markers (bHCG, AFP and PLAP)
ETV and biopsy if hydrocephalus
Stereotactic or endoscopic biopsy if no hydrocephalus
If germinoma then Radiotherapy and Chemotherapy
If not a germinoma then surgical resection
Which pineal region tumours should not be operated on?
Germinomas (as these are radio and chemosensitive)
Malignant tumours with evidence of metastasis (as surgery on the primary tumour does not confer a survival advantage)
What are the approaches to the pineal region?
Supracerebellar infratentorial
Occipital transtentorial (recommended for lesions that can be accessed above the v. of Galen). Note, the tentorium is excised one cm lateral to the straight sinus.
Paramedian infratentorial supracerebellar keyhole (PISKA) performed in park-bench position
Transcallosal (for tumours extending into the CC and 3rd vent)
Microsurgical PISKA approach
Internal occipital vein, BVR, internal cerebral vein and superior vermian vein should be navigated.
What replaces the term PNET?
Embryonal tumours
What are the 4 genetic clusters of medulloblastoma?
What are the 4 histological clusters of medulloblastoma?
Wnt (10%), SSH (p53) (30%), Group 3 (20%) and Group 4 (40%)
Classic, Nodular aka desmoplastic, Extensive nodularity and Large cell aka anaplastic. Note large cell are always high risk. Classic are always standard risk except with SSH p53 mutation, which are high risk.
What is suggested if a patient with a medulloblastoma presents with back pain, radiculopathy or urinary retention?
Drop mets
What are the classical neurological findings in a patient with a posterior fossa mass?
Hydrocephalus
Papilloedema
Truncal / Limb ataxia
Nystagmus
Diplopia
Where do medulloblastomas arise from?
Roof of the 4th ventricle (note ependymomas arise from the floor!)
What are the features of wnt-activated medulloblastomas?
Arise from the middle cerebellar peduncle. 10% of cases.Mostly older children. Good prognosis with mets in 10% at diagnosis. Arise from progenitor cells in the lower rhombic lip.
What are the features of SHH activated medulloblastomas?
All age groups. 30% of all cases. P53 mutant. Cerebellar hemisphere location. Arise from precursors of the external granule layer. Prognosis is good in infants but intermediate in others.
Where do wnt-activated medulloblastomas arise?
From the middle cerebellar peduncle as they arise from precursor cells of the rhombic lip.
What does P53 mutation convey with SHH-activated medulloblastomas?
P53 mutation is a high-risk tumour. P53 WT is a low-risk tumour.
What is the most prevalent type of medulloblastoma?
Group 4
What is the treatment for medulloblastoma?
Maximal safe surgical resection
30% will require a VP shunt
What is sugar coating in medulloblastoma?
Tumour infiltration causing thickening of the arachnoid
How do you risk stratify medulloblastomas post-op?
Standard = GTR no mets and CSF clear. SSH activated P53 WT or Group 3/4
Low = GTR WNT-activated
High risk = >1.5 cm3 residual, mets or CSF cells, SHH activated P53 and large cell histology
What is the Chang classification for medulloblasoma?
A T1-4 M1-4 grading system from the preMRI era. The T is based on size < or > 3 cm and brainstem involvement. The M is based on CSF seeding.
Not used much now as based on old data
What is an ETMR?
Embryonal tumour multilayered rosettes - C19MC amplification on Ch19.
These are extremely aggressive with median survival 6-9 months
What are ATRTs?
Atypical teratoid / rhabdoid tumours (WHO grade 4)
SMARCB4 mutation
An aggressive embryonal tumour with rhabdoid features. May be associated with primary rhabdoid tumours.
Radiologically look like medulloblastomas
Which patients develop precious puberty with pineal region tumours?
BOYS only! The HCG stimulates testosterone production. The lack of raised FSH and LH means this is not converted to oestrogen in girls.
Regarding pineal region tumour markers, what condition can cause a false positively raised AFP?
Liver disease!
What is the treatment for germinoma?
Chemotherapy (cisplatin) +/- radiotherapy depending on CSF cytology + or if there are drop mets
