Sheet 8 Flashcards
What are the 3 types of gliomas?
1) Astrocytomas
2) Oligodendrogliomas
3) Ependymoma
Oligodendrogliomas account for -% of gliomas.
5-15%
Oligodendrogliomas are diagnosed at which ages?
40-50
Where are oligodendrogliomas located?
Mostly in the cerebral hemispheres, mainly in the frontal or temporal lobes, white matter.
What is diagnostic for oligodendrogliomas?
The presence of IDH mutation AND 1p & 19q co-deletion
How do we treat oligodendrogliomas?
With a combination of surgery, chemotherapy, and radiotherapy
What is the average survival rate of a grade 2 oligodendrogliomas?
10-20 years (because of infiltration)
What is the average survival rate of a grade 3 oligodendrogliomas?
5-10 years (because of anaplastic features)
Which grades of oligodendrogliomas don’t exist?
1 and 4
Which has a better prognosis(!):
Grade 3 astrocytoma or grade 3 oligodendroglioma?
Grade 3 oligodendroglioma
What are the characteristics of grade 2 oligodendrogliomas?
1) Infiltrative tumors
2) +/- cysts
3) Focal hemorrhage
4) Calcification
If we see calcifications with a diffuse infiltrating tumor in the radiograph, which tumor is it most likely to be?
Oligodendroglioma
What are the histological characteristics of grade 2 oligodendrogliomas?
1) Sheets of regular cells with spherical nuclei containing finely granular chromatin
2) The nuclei are surrounded by a clear perinuclear halo of cytoplasm (Fried-egg appearance).
3) Delicate network of anastomosing capillaries “chicken-wire”.
4) Calcification in 90% of tumors.
5) Low mitotic activity
6) No spontaneous necrosis.
7) No microvascular proliferation.
What are the histological characteristics of grade 3 oligodendrogliomas?
1) Increased cellularity
2) Easily identifiable mitotic figures
3) Microvascular proliferation, ± necrosis
Where do ependymomas arise?
Next to the ependyma- lined ventricular system, including the central canal of the spinal cord.
Where are ependymomas located?
1) Posterior fossa (60%)
2) Supratentorial (30%)
3) Spinal (10%)
At which age do ependymomas appear?
1) In the first 2 decades of life; near the 4th ventricle (posterior fossa)
2) In adults, the spinal cord and supratentorial ependymomas occur with almost equal frequency
Which clinical outcome is better for completely resected ependymomas:
Supratentorial & spinal
ependymomas or posterior fossa ependymomas?
Supratentorial & spinal
ependymomas
What is the morphology of ependymomas?
Composed of uniform small cells with round to oval nuclei and granular chromatin in a fibrillary matrix and characterized by:
1) Rosette formation
2) Low cell density and a low mitotic count
3) Cilia and microvilli are seen on ultrastructural examination
What are the 2 types of rosettes?
1) Ependymal rosettes: diagnostic hallmark of ependymoma (25%)
2) Perivascular pseudorosettes: not specific for ependymoma.
What are rosettes?
Tumor cells arranged like a
circle around a central structure
What are ependymal rosettes?
Tumor cells arranged around central canal or lumen that resemble the embryologic ependymal canal, with long, delicate processes extending into a lumen.
What are perivascular pseudorosettes?
Composed of tumor cells radially arranged around vessels with an intervening anucleated zone containing thin ependymal processes.
What is the morphology of anaplastic ependymomas?
1) Increased cell density
2) High mitotic rates
3) Necrosis
4) Microvascular proliferation
5) Less evident ependymal
differentiation
What are the neuronal and glioneuronal tumors?
1) Central neurocytoma
2) Ganglioglioma
3) Dysembryoplastic neuroepithelial tumor (DNT or DNET)
What is the shared feature of all neuronal and glioneuronal tumors?
All of them show neuronal
differentiation = when you stain them with immune stains for neurons, they are going to be positive (synaptophysin positive and neurofilament positive)
What is the most common presentation of neuronal and glioneuronal tumors?
Seizures
Which are more frequent:
Neuronal tumors or Gliomas?
Gliomas
What are neuronal tumors composed of?
Cells with neuronal characteristics and express neuronal markers, such as synaptophysin and neurofilaments.
What is a Central neurocytoma, WHO grade 2?
Low-grade neuronal tumor within and adjacent to the lateral ventricle(s) and/or the third ventricle affecting young adults (NO glial component).
What is a Ganglioglioma, WHO grade 1?
Well differentiated glioneuronal tumor affecting children and young adults. composed of a mixture of neoplastic ganglion and glial cells, most commonly in
the temporal lobe.
What is a Dysembryoplastic neuroepithelial tumor (DNT), WHO grade 1?
Low-grade (well differentiated) glioneuronal tumor affecting the cerebral cortex of children and young adults most commonly in the superficial temporal lobe.
What are the 3 oncogenic pathways of medullablastomas?
1) WNT pathway activation
2) Hedgehog pathway activation
3) MYC overexpression
What is the most common CNS neoplasm in immunosuppressed individuals?
Primary CNS Lymphoma
What is the most common subtype of Primary CNS Lymphoma?
Diffuse large B-cell lymphomas
How does Primary CNS Lymphoma present as?
1) Multiple tumor nodules within the brain parenchyma
2) Well-defined
3) Not as discrete as metastases
What is the most common primary CNS germ cell tumor?
Germinoma, testicular seminoma
Where are primary brain germ cell tumors found?
Along the midline, pineal and suprasellar regions
