CNS Tumors: Types, Features, and Diagnostic Criteria

What percentage of brain tumors are primary?

About 50%

What percentage of cancers in children under 15 years old are primary brain tumors?

20%

What are common clinical presentations of CNS tumors?

Focal or generalized seizures, focal neurologic deficits, signs of increased intracranial pressure (ICP)

What is the typical cause of death associated with CNS tumors?

Complications from increased ICP

What factors influence the prognosis of CNS tumors?

Benign or malignant behavior, invasion and destruction of vital centers, surgical accessibility

Are extracranial metastases common in brain tumors?

No, they are rare due to the absence of lymphatics in the brain

Which type of brain tumors are more common in males?

Gliomas

Which type of brain tumors are more common in females?

Meningiomas

What is a common risk factor for meningiomas and gliomas?

Radiation exposure from another malignancy

What are the three types of glial cells that give rise to gliomas?

Astrocytes, ependymal cells, and oligodendrocytes

What is the characteristic growth pattern of astrocytoma grade I?

Well-circumscribed with distinct differences from other astrocytomas

What is a defining feature of pilocytic astrocytoma?

Hairlike structures and a better prognosis

What is the most aggressive form of astrocytoma?

Glioblastoma (grade IV)

What histological features are associated with glioblastoma?

Marked vascular proliferation, necrosis, and pseudo-palisading pattern of cells

What is the prevalence of oligodendrogliomas among primary CNS tumors?

5-15%

What are common characteristics of oligodendrogliomas?

More chemosensitive, associated with calcification, and present in adulthood

What is the typical location for ependymomas?

Near ependymal-lined ventricles or the spinal cord central canal

What is a common feature of ependymomas in terms of growth?

CSF dissemination is common

What is the prognosis of myxopapillary ependymoma?

Depends on the extent of excision; biologically benign

What is the most common brain tumor in children?

Medulloblastoma

What histological features are associated with medulloblastoma?

Homer-Wright rosettes and high cellularity with increased mitoses

What type of tumor is a meningioma?

The most common extra-axial tumor and the most common non-glial brain tumor in adults

What is the relationship between meningiomas and gender?

More common in females

What are psammoma bodies?

Concentric laminations seen in meningiomas

What is the genetic basis of Neurofibromatosis type 1?

Found on Chromosome 17

What is the genetic basis of Neurofibromatosis type 2?

Found on Chromosome 22

What are the common sites for germ cell tumors?

Pineal gland and suprasellar region

What is the typical presentation of primary CNS lymphoma?

Non-Hodgkin's lymphoma, usually of B cell origin, with a poor prognosis

How do metastatic tumors spread to the brain?

Via the hematogenous route, as the brain lacks lymphatics

What symptoms are common in CNS metastasis?

Headache, focal neurological signs, seizures, and papilledema

What is the prognosis for untreated CNS metastasis?

Survival rate is typically weeks; treatment may extend it to 3-6 months