Meningioma

Meningioma

1. Meningioma Dr vaishal shah DM neurology resident Govt. medical college,kota

2. Introduction Meningioma is the most common of all intracranial neoplasms. Over a third of all primary intracranial neoplasms. Female predominance ( F/M – 2/1 ). Peak occurrence is in the sixth and seventh decades (mean = 65 years).

3. Introduction Although meningioma accounts for slightly less than 3% of primary brain tumors in children, meningioma still represents the most common durabased neoplasm in this age group. NF2-related meningiomas occur at a significantly younger age compared with nonsyndromic meningiomas. Symptoms relate to size and tumor site. < 10% of meningiomas become symptomatic.

4. Types WHO grade 1 - most common type, benign. WHO grade 2 - more aggressive clinical behavior and less favourable outcomes. The most aggressive form of meningioma, corresponding to WHO grade III, is anaplastic ("malignant") meningioma .

5. Etiology Ionising radiation is the only established risk factor. The dose-related time interval to tumor development varies from 20 to 40 years.

6. Etiology NF2 mutations are detected in most meningiomas associated with type 2 neurofibromatosis (NF2) and are found in up to 60% of sporadic meningiomas. NF2 mutant meningiomas originate along the posterior or superior cerebral hemispheres , the posterior and lateral skull base, and the spinal cord. Non-NF2 meningiomas are usually benign and originate from the medial skull base and anterior cerebral hemispheres.

7. Size and Number Meningiomas vary widely in size. Most are small (< 1 cm) and found incidentally. Some—especially those arising in the anterior fossa from the olfactory groove —may attain large size before causing symptoms.

8. Imaging – CT Round or lobulated, sharply demarcated, extraaxial dura-based mass that buckles the cortex inward. 3/4 of meningiomas are mildly to moderately hyperdense compared with cortex. 1/4 are isodense . Peritumoral vasogenic edema , seen as confluent hypodensity in the adjacent brain, is present in about 60% of all cases.

9. CT The vast majority of meningiomas enhance strongly and uniformly 25% demonstrate calcification. Focal globular or more diffuse sand-like (" psammomatous ") calcifications occur. Frank necrosis or hemorrhage is rare.

10. CT Bone CT may show hyperostosis that varies from minimal to striking. Striking enlargement of an adjacent paranasal sinus may occur with skull base meningiomas. Bone involvement by meningioma occurs with both benign and malignant meningiomas and is not predictive of tumor grade.

11. MRI T1 - Meningiomas are typically iso to hypointense compared with cortex. T2 - Iso to moderately hyperintense compared with cortex. CSF-vascular "cleft“ is seen as a hyperintense rim interposed between the tumor and brain on T2. A number of "flow voids" representing displaced vessels are often seen within the "cleft.“ Sometimes a "sunburst" pattern can be identified radiating toward the periphery of the mass.

12. MRI FLAIR - Varies from iso- to hyperintense. Useful for depicting peritumoral edema seen in half of the patients. Peritumoral edema is related to the presence of pial blood supply and VEGF expression, not tumor size or grade. T1+C - Over 95% enhance strongly and homogeneously. Dural tail is seen in majority. It enhances more intensly and more uniformly than tumour itself. Dural tail is not pathognomic .

13. DWI - Most meningiomas do not restrict on DWI. MRS - Alanine (Ala, peak at 1.48 ppm) peak is sensitive. Glutamate-glutamine ( peak at 2.1-2.6 ppm) and glutathione (peak at 2.95 ppm) may be more specific potential markers. Perfusion MR - helpful in distinguishing TM from atypical/malignant meningiomas. High rCBV in the lesion or in the surrounding edema suggests a more aggressive tumor grade.

14. Occasionally skull base meningiomas adjacent to a paranasal sinus cause massive enlargement of the sinus, a condition known as pneumosinus dilatans .

15. Sunburst of vessels

16. Atypical Meningioma 10-15% of all meningiomas. Most atypical and malignant meningiomas arise from the calvaria. The skull base is a relatively uncommon location for these more aggressive lesions. 50% of atypical meningiomas invade the adjacent brain. So no cleft is seen.

17. Imaging Indistinct borders and heterogenous lesion. Frank bone invasion with osteolysis is common. Better seen on CT. Absent of CSF – Vascular cleft. Peritumoral edema .

18. Contrast enhancement is strong but often quite heterogeneous. ADC is significantly lower in atypical and malignant meningiomas. Perfusion MR may show elevated rCBV , especially in the peritumoral edema .

19. Clear cell type atypical meningioma

20. Anaplastic meningioma Rare 1-3% of meningioma Male predominance Imaging triad – Extracranial mass, osteolysis, “mushrooming” intracranial tumour.

21. Papillary meningioma – grade 3

22. Thank you