41. Glial central nervous system tumors

Majority of CNS tumors are?

Primary tumors (60-80%)

One way to distinguish primary CNS tumors from brain metastases?

- Primary tumors of the CNS are usually solitary masses

- Brain metastases are often multifocal

Unique characteristics of tumors of the CNS?

- Dont have detectable premalignant or in situ stages

- Even low grade tumors may cause severe symptoms, due to the closed nature of the skull

- The anatomical site of the neoplasm can influence the outcome independent of the histological subtype, due to local effects

- Rarely metastases outside the CNS

- Different grading system

What is the only known predisposing factor to brain tumors?

Ionizing radiation to the head

What are drop metastases?

When brain tumors disseminate with the CSF

- and reach the lower regions of the spinal cord

Symptoms of CNS tumors?

- Progressive headaches

- Focal neurological symptoms

- Vomiting

- Sudden onset of epilepsy

Focal neurological symptoms can be?

- Aphasia

- Deafness

- Visual abnormalities

How can we classify CNS tumors?

- Neuroepithelial tumors

- Meningeal tumors

- Other primary tumors

- Metastases

What can we further divide neuroepithelial tumors into?

- Gliomas

- Neuronal and mixed neuronal-glial tumors

- Choroid plexus tumors

- Embryonal tumors

Grading of CNS tumors? how is it different from the normal grading system?

The classification system used is based on the histological characteristics, like atypia, mitosis, endothelial proliferation and necrosis

- the grade of the tumor doesnt depend on the degree of differentiation, but rather on the histological type

Characteristics of grade I?

- Benign

- Slow growing

- Cells almost normal

- Rarely recurs after treatment

- Good prognosis

Characteristics for grade II?

- "Semi-malignant"

- Atypia of cells

Characteristics for grade III?

- Malignant

- Fast growing

- Anaplastic cells

- High recurrence

- Poor prognosis

Characteristics for grade IV?

- Most malignant

- Fastest growing

- Microvascular proliferation

- Necrosis and haemorrhage often present

- Worst prognosis

How can grade I tumors have poor prognosis?

If the tumors arise in areas where they are impossible to resect, of treat completely

Which localization has the worst prognosis?

Tumors localized next to the basal ganglia and internal capsule

What are glial cells?

Cells in the nervous system that support, nourish, and protect neurons

- oligodendrocytes

- astrocytes

- ependymal cells

- microglial cells

What are gliomas?

Tumors that arise from the glial cells

- oligodendroglial tumors

- astrocytic tumors

- ependymal tumor

How can we classify the gliomas?

- Diffuse astrocytic and oligodendroglial tumors

- Other astrocytic tumors

- Ependymal tumors

Diffuse astrocytic and oligodendroglial tumors?

- Diffuse astrocytoma

- Anaplastic astrocytoma

- Glioblastoma

- Oligodendroglioma

- Anaplastic oligodendroglioma

Diffuse astrocytoma?

Grade II glioma

- most commonly located in the frontal or temporal lobes

Anaplastic astrocytoma?

Grade III glioma

- most commonly located in the frontal or temporal lobes

Histology of anaplastic astrocytoma?

Show severe atypia, mitotic activity but no necrosis

Glioblastoma?

Grade IV glioma

- commonly affects the cerebral hemispheres bilaterally, forming a characteristic butterfly pattern

- most common primary CNS tumor

Histology of glioblastoma?

Similar to anaplastic astrocytoma

- just with the addition of pseudopalsiding necrosis and microvascular proliferation

Oligodendroglioma?

Grade II glioma

- most commonly occurs in the frontal or temporal lobes

Anaplastic oligodendroglioma?

Grade III glioma

- more aggressive than the non-anaplastic oligodendroglioma

Other astrocytic tumors?

- Pilocytic astrocytoma

- Pleomorphic xanthoastrocytoma

Pilocytic astrocytoma?

Grade I glioma

- most commonly located in the cerebellum and optic pathways

- most common in children

Ependymal tumors?

- Myxopapillary ependymoma

- Ependymoma

- Anaplastic ependymoma

Ependymoma?

Malignant tumor of ependymal cells (line the ventricular system)

- range from grade I to grade III

Ependymomas usually occur where in adults? children?

- Spinal cord in adults

- Near the fourth ventricle in children = hydrocephalus

What are ependymomas associated with?

Neurofibromatosis type II

What does the tumor cells of ependymomas form?

Elongated structures called rosettes and pseudorosettes