Brain Tumours — Metastases, Gliomas & Meningiomas

🧠 Brain Tumours

Metastases vs primary tumours, gliomas vs meningiomas, clinical presentation, and the neurosurgeon’s full toolkit — from dexamethasone to Gamma Knife.

The Golden Rule — Metastases First

When a brain tumour appears on a scan, statistically it came from somewhere else. Before entertaining any primary brain tumour diagnosis, a metastatic source must be thoroughly excluded. This single rule prevents an enormous number of diagnostic errors.

30–50%

of all brain tumours are metastases — the most common

15%

of all cancer patients present with brain metastasis as their first symptom

50%

of primary brain tumours are gliomas — three-quarters are high-grade

14.6mo

median survival of GBM (WHO Grade IV) — the most common primary brain tumour

🌍

Cerebral Metastases

Most common brain tumour overall (30–50%)

OriginLung, Breast, Bowel, Melanoma, Renal Cell (Big 5)

LocationGrey-white matter junction — sudden vessel calibre change traps emboli

Multiplicity~50% are solitary on CT at presentation; multiple = more pathognomonic of mets

CT appearanceRounded lesion with vasogenic oedema, ring enhancement on contrast

TreatmentSurgical resection (solitary + accessible) or stereotactic radiosurgery ± whole-brain radiotherapy

GoalPalliation and quality of life — rarely curative unless single met + controlled primary

🔴

Glioblastoma (GBM)

WHO Grade IV — Most common primary brain tumour

OriginGlial cells (astrocytes) — infiltrates surrounding brain extensively

HistologyMicrovascular proliferation + pseudopalisading necrosis = diagnostic

CT/MRIIrregular ring-enhancing lesion with central necrosis and surrounding oedema

PrognosisMedian survival 14.6 months with maximal treatment

SurgeryDebulking only — cure is impossible; infiltrating cells cannot be fully resected

AdjuvantRadiotherapy + Temozolomide chemotherapy (Stupp protocol)

🟢

Meningioma

WHO Grade I — Usually benign and resectable

OriginArachnoid cap cells — grows attached to dura, compresses brain from outside

PathologyRubbery, lobulated, dura-attached mass. Psammoma bodies (calcifications) on histology.

CT/MRIHomogeneously enhancing extra-axial mass with “dural tail” sign. May be calcified.

GrowthSlow-growing — often incidental. Compresses brain, does not infiltrate.

SurgeryComplete resection is usually curative (Simpson Grade I–II excision)

PrognosisExcellent for Grade I. Grade II/III (atypical/malignant) have higher recurrence rates.

The Fundamental Surgical Distinction

Meningioma compresses the brain from the outside — it has a clear surgical plane between tumour and brain. Complete resection is achievable and often curative. The brain springs back when the mass is removed.

Glioma infiltrates the brain from the inside — tumour cells migrate along white matter tracts far beyond the visible tumour mass. There is no clean margin. You cannot resect a glioma to cure; you can only debulk to relieve mass effect and prolong survival.

This distinction — compressor vs infiltrator — determines the entire surgical philosophy and patient counselling for each tumour type.

You're reading the free preview.More detailed sections, comparisons, mnemonics and exam pearls continue below — for subscribers.