8A. Gliomas (and brain tumours in general)

Brain tumours in general

Definition and epidemiology

In adults, secondary brain tumours are 10x as common as primary ones.

Etiology

  • Most common tumours in childhood
    • Craniopharyngioma
    • Medulloblastoma
    • Cerebellar astrocytoma
  • Most common tumours in adulthood
    • CNS metastases
    • Meningioma
    • Glioblastoma
    • Pituitary tumours

Pathomechanism

According to the Monroe-Kellie doctrine, a brain tumour must decrease CSF flow and cerebral blood flow. In the beginning phase, CSF and CBF flow can decrease to compensate for the increased ICP. Eventually the compensatory mechanisms are exhausted, causing large increase in ICP.

Clinical features

  • Headache
  • Vertigo
  • Increased ICP
    • Nausea, vomiting
    • Papilloedema
  • Focal neurological symptoms
  • Focal epilepsy

Prognosis

There are many prognostic factors which decide the prognosis of the patient.

  • Tumour grade, which depends on the histological type
  • Biogenetical markers of tumour
  • Karnofsky Performance Status (KPS)
  • Age of patient
  • Comorbidities
  • Presence of metastasis of CSF

Diagnosis and evaluation

The gold standard for diagnosis is contrast-enhanced MRI.

The majority of cases undergo biopsy and histopathology. In many of the cases the biopsy isn’t conclusive or diagnostic, in which case we might repeat biopsy, or the precise histologic type of the tumour won’t be known until surgical removal. Histopathology is usually repeated after surgical removal. Brainstem tumours can’t be biopsied.

Treatment

Complete surgical resection is required for cure, but debulking surgery may improve the prognosis in cases where cure isn’t possible. Surgical resection in brainstem is rarely possible

Gliomas

Definition and epidemiology

Gliomas are tumours which originate from glial cells like astrocytes, oligodendrocytes, and ependymal cells. They’re the second most common primary brain tumours in adults (after meningioma). There are three types, based on the cell of origin:

  • Astrocytoma
  • Oligodendroglioma
  • Ependymoma

Astrocytomas are graded like this:

  • Grade I astrocytoma = pilocytic astrocytoma
  • Grade II astrocytoma = diffuse astrocytoma
  • Grade III astrocytoma = anaplastic astrocytoma
  • Grave IV astrocytoma = glioblastoma

Higher grades have more mitosis, more atypia, worse prognosis.

Glioblastoma is the most common glioma in adults. Pilocytic astrocytoma is the most common glioma in children.

Diagnosis and evaluation

Aside from general evaluation of brain tumours, for gliomas it’s important to test for IDH and 1p/19q codeletion. Tumours with IDH mutation or 1p/19q codeletion has better prognosis than wildtype.


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