Meningioma
- Lesion
Meningiomas grow from the brain's covering, are usually slow and benign, and press on the brain rather than invade it.
What it is
Meningiomas are tumours of arachnoid cap cells attached to the dura. They are the commonest primary intracranial tumour in adults, more frequent in women, and usually benign (grade 1). They grow along the falx, convexity, sphenoid wing, olfactory groove, tentorium and spinal canal, compressing the brain. Loss of NF2 is the commonest driver; multiple meningiomas suggest neurofibromatosis type 2 or prior radiation. Higher-grade forms recur and can invade the brain.
Structure
- Gross: firm, rounded, well-demarcated mass that indents the brain and can be peeled away; en plaque forms spread as sheets over dura.
- Micro: syncytial cells in lobules and whorls, fibroblast-like spindle cells in fibrous variant.
- Markers: EMA, progesterone receptor and SSTR2A positive.
Meningioma grades
| CNS WHO grade | Defining features | Behaviour |
|---|---|---|
| Grade 1 | Usual variants (meningothelial, fibrous, transitional, psammomatous), low mitotic rate | Slow growth; cured by complete removal |
| Grade 2 (atypical) | Increased mitoses, brain invasion, or clear cell or chordoid variant | Recurs more often |
| Grade 3 (anaplastic) | Very high mitotic rate, carcinoma- or sarcoma-like, TERT promoter mutation or CDKN2A/B deletion | Aggressive, recurs, can metastasise |
Clinical notes
- Often found by chance; symptoms depend on site: seizures, focal deficits, anosmia (olfactory groove), visual loss (sphenoid wing).
- In children or young adults, a meningioma should raise suspicion of NF2 or prior radiation.
Test yourself
Think of the answer, then tap the question to see it.
What are psammoma bodies in a meningioma?
Round laminated calcifications that form in the centre of cell whorls.
Which gene is most often lost in meningiomas?
NF2 (merlin), also mutated in neurofibromatosis type 2.
Which finding makes a meningioma grade 2 even without many mitoses?
Invasion of brain tissue, or the clear cell or chordoid variant.
Connections
Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.
Sources: Meningioma: Diagnosis and Treatment - NCI (National Cancer Institute, 2026).
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Representative model, for educational purposes only.