Tumors

Definitions

Tumor: Abnormal group of cells that are clumped together

Metastatic CNS tumors

  • Tumors that originated somewhere else and travelled into the brain

  • Well-defined (clumps of foreign cells in brain)

  • Usually (80%) in the cerebral hemispheres

Primary CNS tumors

  • Tumors that originate (and stay) in the CNS

    • Malignant vs benign

  • Incidence generally correlated with age

Types of CNS tumors

  • Meningiomas- grow in the meninges

    • Benign, easily removed surgically

    • Most common type of CNS primary tumor

  • Ependymoma- from ependymal cells (they make CSF) in ventricles

    • Benign, treated with radiation/chemicals

  • Medulloblastoma- from blast cells in medulla

    • Most common primary CNS tumor in children

    • Infratentorial (from video)

    • Metastasize through CSF (drop metastasis) to base of spine

    • Malignant- treated with surgery and aggressive radiation and chemotherapy

  • Neuromas (nerve sheath)- develop around cranial nerves, affect Schwann cells

    • Often auditory/ vestibular nerve

  • Gliomas- glioblastomas, astrocytomas, oligodendrogliomas

    • Most common types of CNS primary tumor

    • Malignant

    • Caused by spontaneous genetic mutations- not inherited

  • X-rays cause brain cancer (not mris)

    • X-rays were first used to fit shoes

CD 133

  • Tumors have lots of types of cells

    • Some are CD 133+

    • CD 133+ cause tumors, CD 133- do not

Grading of Tumors

  • Atypical cell types

  • Atypical cell nuclei

  • Mitosis- cell division

  • Necrosis - dead cells

  • Vascular proliferation- new blood vessels

  • Who grades 1-4 (I-IV)

    • I-II abnormal cells or nuclei, but no mitosis

    • III mitosis and at least one other feature

    • IV at least three of the five features

Genetics of Gliomas

  • Oncogenes

    • Receptor tyrosine kinases (RTKs) - receptors for growth factors

  • Tumor suppressor genes

  • Glioma cells have mutations in both classes of gense

  • Mutations are spontaneous and not heritable

    • Somatic = happens in cells of the body, but not sperm or eggs (don’t get passed on to children)

Metastasis

  • From body to the CNS is common = metastatic CNS tumors

  • From CNS to body= basically doesn’t happen

  • Within CNS - happens easily and quickly

    • Along blood vessels

    • Along nerves

    • Through CNS tissue

      • Tumors have some cells that make Matrix metalloproteinases that chews up the extracellualr matrix so that the tumor can spread through the brain tissue

    • Through subarachnoid space (under meninges)

Glioma cells can squeeze through really tight spaces (they squeeze all the water out of themselves and can get through small gaps then rehydrate themselves and go back to being a tumor cells.

Gliomas create their own blood vessels

  • If you remove a tumor since they have a lot of blood vessels, theres a risk of bleeding to death

  • Now they are good at cauterizing blood vessels to control bleeding

Symptoms of a CNS tumor

  • Depends on location of tumor

  • Headache, nausea, vomiting- due to increased intracranial pressure

  • Seizures, muscle weakness, vision problems, changes in personality (vision is often first symptom report or seizures)