CNS (mostly) Tumors Flashcards
What are the 4 categories of classification of Brain tumors as per WHO grading?
I. Well circumscribed, slowly progressive can often be cured by resection. “Benign.”
II. Infiltrative with low proliferation, higher chances of recurrance.
III. Histologically malignant and require more aggressive adjuvant tx.
IV. Highly malignant and rapidly fatal.
What are the two markers for astrocytoma?
GFAP (Glial Fibrillary Acidic Protein) and Glutamine Synthetase.
What are the 4 WHO types of astrocytomas?
Type I is Juvenile Pilocytic Astrocytoma, II is Fibrillary, III is Anaplastic, and 4 is Glioblastoma multiforme.
Who usually are more prone to astrocytomas?
80% of all adult primary brain tumors are astrocytomas, and they present in the cerebral hemispheres usually from 40-60 yrs of age.
What are some signs and symptoms experienced by patients with astrocytomas?
Seizures, headches, nausea, vomitting, focal neuro headaches.
Describe a diffuse astrocytoma?
Mild/moderate increase in glial cellularity, variable nuclear pleomorphisms, GFAP+ astrocytic processes which makes it look “fibrillary.” Transition between normal and neoplasm is indistinct, and it is considered WHO grade II.
Describe an anaplastic astrocytoma?
WHO grade III, more densely cellular, greater nuclear pleomorphism and mitotic activity.
What is “Gemistocytic Astrocytoma?”
The predominant neoplastic astrocyte is brightly eosinophilic with many stout processes.
Given time, what do astrocytomas tend to become?
Tends to become anaplastic or even a type IV if left untreated..
Describe the glioblastoma (previously known as glioblastoma multiforme).
WHO type IV, has the things in type III (pleomorphic cells, increased mitosis, etc), but in addition there is necrosis (very distinct) and vascular/endothelial cell proliferation.
Describe the type of necrosis seen in WHO type IV?
Often serpentine, occurs in areas of hypercellularity, giving the apprearance of “pseudopalisading” of malignant nuclei. (Pseudopalisading necrosis, pseudopalisading meaning cells line up like a picket fence around the necrosis)
What is one proposed factor that leads to vascular proliferation of a glioblastoma?
Malignant astrocytes might secrete VEGF in response to hypoxia (for when tumor grows bigger and requires more oxygen), resulting in vascular proliferation.
What is the difference between primary and secondary glioblastomas? Age and genetic associations?
Primary may arise w/o previous low grade tumor, seen more in older patients. Associated with amplification of the epidermal growth factor receptor gene. Secondary occurs after a previous low grade astrocytoma, which is associated with a mutated p53 gene, and is seen more in younger patients.
Median life expectancy of glioblastoma?
8-10 months regardless of primary or secondary.
What side of the brain does glioblastomas tend to stay at?
They used to be called “butterfly tumors” because they will always cross the midline and thus end up being in both sides of the brain.
In order to be a type IV glioblastoma, what must be present?
Pseudopalisading necrosis + vascular proliferation.
What is the “benign” astrocytoma? What age group is this common?
Grade I, called pilocytic astrocytoma found in children mostly.
What is the classic appearance of this kind of tumor (pilocytic astrocytoma)?
Cystic mass with an enhancing mural nodule.
Where can pilocytic astrocytoma occur? How are they treated?
Frequently seen in the cerebellum but can also be found in the floors and walls of the 3rd ventricle, suprachiasmatic region, optic nerves, hemispheric and spinal. Can be tx-ed surgically if tumor is in an approachable area. Prognosis is good.
What are the classic signs in a histo slide of a pilocytic astrocytoma?
Distinctive bipolar cells with long, thin, hair like GFAP+ processes, and Rosenthal fiber.
Histologically what can be present (although not distinctive) of pliocytic astrocytoma?
Rosenthal fibers.
Buzzwords for Pilocytic astrocytoma?
Children, cerebellum, cystic with a mural nodule, relatively benign. Rosenthal fibers.
Who tends to get oligodendrogliomas?
Older patients in their 40-50’s, only ~15% of all gliomas.
What is a common previous complaint of patients with oligodendrogliomas?
Often had seizures for several years and other neurological complaints.
Where do oligodendrogliomas present? How do they look?
Generally in the cerebral hemispheres esp in white matter. They are well circumscribed, gelatenous gray mass, focal hemorrhages and calcification.
How do oligodendrogliomas present microscopically?
Looks like “fried eggs,” sheets of regular cells with spherical nuclei w/ finely granular chromatin surrounded by a clear halo of cytoplasm.
How do oligodendrogliomas receive their blood supply, are they calcified, and their WHO classification and mitotic activity?
Delicate network of anastamosing capillaries are their blood supply (chicken wire with the capillary presentation), 90% show calcification, WHO grade II and has very little mitotic activity.
Which are the worse variant of oligodendrogliomas and how do they present?
Anaplastic oligodendrogliomas, these are more rare. Grade III. Increased cell density, nuclear anaplasia, increased mitotic activity and necrosis.
What is the most common genetic change for oligodendrogliomas?
Loss of heterozygosity of chromosomes 1p and 19q.
Which has a better prognosis, oligodendrogliomas or astrocytomas?
Oligodendrogliomas have a 5-10 year survival rate with tx, thus better prognosis.
What are Ependymomas?
Considered glial cell tumor even though it comes from ependymal cells. Appears where ependymal cells are found (in the ventricles, particularly in the 4th ventricle) and most common up to 20 years of age.
If adults have ependymomas, where will it present?
Central canal of the spinal cord, especially in neurofibromatosis, type II. It is the most common spinal cord tumor in adults.
In children how do ependymomas look and why do they have a relatively poor prognosis (4 yr median survival rate)?
They are solid or papillary masses that extends from the floor of the ventricle. It tends to be located near pontine and medullary nucleus so surgical resection is impossible.
How would a child present with ependymoma if it is present in the posterior fossa?
Hydrocephalus due to progressive obstruction of the 4th ventricle and CSF dissemination.
How do Ependymomas present microscopically?
“Perivascular Pseudo-rosettes,” tumors form rosettes that look like embryonic ependymal canal with long processes that extend into the lumen (they tend to be perivascular). Regular oval nuclei w/ granular chromatin. Between nuclei however there is dense fibrillary background giving rise to the pseudo-rosettes.
Grade of Ependymomas?
II, anaplastic is III, and despite the relatively good grading the location makes this tumor fatal.
Where does the tumor rise in a child with ependymoma?
4th ventricle or foramen of Lushka/Magendie.
Which type of ependymomas are usually parenchymal? Where do Ependymomas metastisize?
Supratentorial ependymomas. CNS metastasis common.
