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Meningioma

Summary

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  • Meningiomas are typically slow-growing, benign tumours arising from arachnoid cap cells of the meninges
  • Most common primary intracranial tumour in adults
  • Characteristic imaging findings include dural-based extra-axial masses with homogeneous enhancement and dural tail sign

Pathophysiology

  • Arise from arachnoid cap cells in the meninges
  • WHO classification grades:
    • Grade I (benign): 80-90% of cases
    • Grade II (atypical): 5-15% of cases
    • Grade III (anaplastic/malignant): 1-3% of cases
  • Common genetic alterations:
    • NF2 gene mutations (50-60% of sporadic cases)
    • TRAF7, KLF4, AKT1, and SMO mutations

Demographics

  • Account for approximately 36% of all primary intracranial tumours
  • Peak incidence: 6th-7th decades of life
  • Female predominance (2:1 female-to-male ratio)
  • Risk factors:
    • Prior radiation exposure
    • Neurofibromatosis type 2
    • Hormonal factors (e.g., pregnancy, oral contraceptives)

Diagnosis

  • Often asymptomatic and discovered incidentally
  • Clinical presentation depends on tumour location:
    • Headaches
    • Seizures
    • Focal neurological deficits
    • Visual disturbances
  • Diagnosis primarily based on imaging findings
  • Histopathological confirmation required for definitive diagnosis

Imaging

  • CT:
    • Hyperdense, well-circumscribed extra-axial mass
    • Calcifications in 20-30% of cases
    • Hyperostosis of adjacent bone
  • MRI:
    • T1: Isointense to slightly hypointense to gray matter
    • T2: Variable signal intensity
    • T1 post-contrast: Intense, homogeneous enhancement
    • Dural tail sign: Linear enhancement extending from tumour along dura
    • DWI: Generally no restricted diffusion
  • Angiography:
    • Sunburst appearance of feeding vessels
    • Tumour blush in arterial phase

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  • A 50-year-old patient presented with a headache and behavioural changes.
  • Symptoms improved or resolved following debulking.

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  • Patient presented initially presented with headache and proptosis.
  • CT showed mixed hyperostosis and luceny of the right sphenoid bone.
  • MRI showed enhancing soft tissue in the middle cranial fossa, temporal fossa, and orbit (causing proptosis).

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  • 60-year-old patient had an MRI following trauma.
  • A incidental enhancing dural lesion lesion involving the cavernous sinus (and Meckel's cave) was consistent with a meningioma.

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  • 50-year-old patient presented with headache.
  • MRI showed an avidly enhancing lesion containing trace amounts of calcium arising from the anterior skull base.
  • The ipsilateral frontal sinus was asymmetrically enlarged - representing pneumosinus dilatans.

panels-1 * 55-year-old patient presented with a progressively worsening headache. * MRI showed a large avidly enhancing lesion occluding the superior sagittal sinus and eroding into the skull. * Final histopathology revealed an atypical meningioma that was treated with radiotherapy following resection.

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  • A 50-year-old patient presented with a frontal headache.
  • MRI showed a large enhancing right paramedian mass lesion associated with extensive vasogenic oedema.
  • T2-hypointensity in the medial part of the lesion was caused by calcification.

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  • A 60-year-old patient presented with a headache.
  • MRI showed an avidly enhancing lesion within the trigone of the left lateral ventricle.
  • An intraventricular meningioma was diagnosed following resection.

Differential diagnosis

Differential Diagnosis Differentiating Feature
Schwannoma Located in basal cisterns, dumbbell-shaped appearance
Pituitary adenoma Centered in sella turcica, hourglass shape through diaphragma sellae
Dural metastasis Irregular enhancement; adjacent bone destruction rather than hyperostosis; more parenchymal oedema; no dural tail
Hemangiopericytoma Mushroom-shaped; intense heterogeneous enhancement; more lobulated margins; absent dural tail
Solitary fibrous tumour Hypointense on T2-weighted MRI; intense heterogeneous enhancement; may have flow voids
Lymphoma Diffuse enhancement; restricted diffusion on DWI; periventricular location; no dural tail
Tuberculoma Ring-enhancing lesion with central T2 hypointensity; surrounding oedema; no dural tail
Sarcoidosis Multiple dural-based lesions; associated cranial nerve and parenchymal involvement; no adjacent hyperostosis