Investigations
1st investigations to order
MRI brain or spine with and without contrast
Test
The diagnostic study of choice in suspected meningioma.
Around half of all meningiomas are found at the skull base (anterior, middle, or posterior cranial fossa), with around 40% occurring at the convexity, falx, or parasagittal regions.[49] Between 7% to 12% of all meningiomas occur at spinal sites.[51]
Result
dural-based mass, homogeneously contrast-enhancing tumour (possibly with surrounding cerebral oedema), dural tail, cerebrospinal fluid cleft
Investigations to consider
CT brain or spine
Test
Indicated if concern exists about any bone involvement (e.g., loss of vision caused by hyperostosis around the optic nerve or involvement of the 8th cranial nerve) or if MRI is contraindicated (e.g., in patients with certain types of pacemakers or shrapnel/metal in their body).
CT may add complementary information demonstrating hyperostosis associated with the tumour or calcifications, which may be present in a significant percentage of patients. Calcification within a meningioma usually indicates a slower-growing tumour.[52]
Result
bony changes (hyperostosis) or calcification (25%); contrast-enhancing tumour, possibly with surrounding oedema, enhancing dural tail
somatostatin receptor PET/CT
Test
PET/CT can be used to detect the somatostatin analogues DOTA-D-Phe1-Tyr3-octreotate (DOTATATE) or DOTA-D-Phe1-Tyr3-octreotide (DOTATOC) that are labelled with a radionuclide such as gallium-68 or yttrium-90. Although not yet standard clinical practice, somatostatin receptor PET/CT can help confirm the diagnosis, or distinguish residual or recurrent tumours from postoperative scarring.[46][53][54] It may also be useful in radiation planning to delineate the target volume.[47][55][56]
Result
involved sites show increased uptake
cerebral angiography
Test
Not for diagnostic purposes. Angiography may be useful for preoperative planning to evaluate venous sinus patency and tumour involvement.[47]
Result
vascular tumour, supplied primarily by external carotid supply
histopathology of surgical resection
Test
Surgical resection may be considered where diagnosis is uncertain based on radiographical findings.[46] Histopathology evaluation is with standard haematoxylin and eosin staining.
Result
wide range of histopathological appearances: the mitotic index and the absence of calcification may indicate a faster-growing tumour; there are significant differences in mitotic indices among tumour grades; the vast majority of meningiomas stain for epithelial membrane antigen (EMA), and somatostatin receptor 2A (SSTR2A), and vimentin positivity is found in all meningiomas; diagnostic ultrastructural features include copious vimentin filaments, complex interdigitating cell processes, and desmosomal intercellular junctions
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