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PH-NE08

Tumours of the brain and spinal cord

How glial and other cells of the brain and spinal cord give rise to tumours, how the WHO classification combines microscopy with molecular markers, and why a tumour’s site, oedema and mass effect decide what it does.

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  • 5 steps · 10 questions
  • 3D normal anatomy

By the end, you can

  • Relate the cells of the brain and spinal cord to the main tumours that arise from them, and explain why metastases are the commonest brain tumours in adults.
  • Explain how IDH mutation and 1p/19q codeletion separate astrocytoma, oligodendroglioma and glioblastoma, and what a CNS WHO grade expresses.
  • Describe the gross and microscopic appearance of glioblastoma, oligodendroglioma, pilocytic astrocytoma, ependymoma, primary CNS lymphoma and metastases.
  • Explain how vasogenic oedema, blocked CSF flow and herniation turn a growing tumour into raised intracranial pressure.
  • Explain why a tumour’s location often matters more than its histology, in the brain and in the spinal canal.
  • Recognise the classic microscopy (pseudopalisading necrosis, fried-egg cells and chicken-wire vessels, Homer Wright rosettes, perivascular pseudorosettes), the grading and molecular groups and the key tests, and explain how surgery, radiotherapy, temozolomide (and why MGMT matters), steroids and radiosurgery act.

What it is

Primary CNS tumours arise from the cells of the brain and spinal cord; secondary (metastatic) tumours spread there from cancers elsewhere and are commoner in adults. The largest primary group is the gliomas, tumours resembling glial cells, which the WHO classification (5th edition, 2021) names by an integrated diagnosis combining microscopy with molecular markers. Tumours of the meninges and nerve sheaths have their own lesson.

6 types to tell apart
Adult-type diffuse gliomas
Astrocytoma, IDH-mutant; oligodendroglioma, IDH-mutant and 1p/19q-codeleted; and glioblastoma, IDH-wildtype. All infiltrate the brain widely.
Circumscribed astrocytic gliomas
Such as pilocytic astrocytoma: well demarcated, mostly in children and young adults, often in the cerebellum, CNS WHO grade 1.
Ependymal tumours
From the lining of the ventricles and central canal; classified by site (supratentorial, posterior fossa, spinal) and molecular group.
Embryonal tumours
Such as medulloblastoma of the cerebellum in children: small primitive cells that can spread through the CSF.
Primary CNS lymphoma
Usually a diffuse large B-cell lymphoma confined to the brain, spinal cord or eyes.
Metastases
The commonest brain tumours in adults, most often from lung, breast, melanoma, kidney and colorectal cancers.

US spelling: tumours → tumors.

Normal function

Neurones, glia and the lining of the ventricles

The brain and spinal cord are built of neurones and the more numerous supporting glial cells. keep the ionic environment steady, take up transmitters and spread end-feet over , helping to form the blood–brain barrier. wrap round segments of several axons, are the resident immune cells, and line the ventricles and the central canal of the cord.

Mature almost never divide, so tumours made of neurones are uncommon. Most primary tumours resemble glial or ependymal cells, or arise from embryonal precursor cells in children, from lymphocytes, or from the meninges and nerve sheaths, which a separate lesson covers.

The whole system sits inside the rigid skull and spinal canal, bathed in cerebrospinal fluid (CSF) that flows from the ventricles to the surface. There is little spare room. The brain tissue itself has no lymphatic vessels, and primary brain tumours very rarely spread outside the central nervous system: their harm comes from what they do inside it.

Point to it on the model