Sphenoid Wing Meningioma Workup

Updated: Nov 11, 2016
  • Author: Bhupendra C K Patel, MD, FRCS; Chief Editor: Hampton Roy, Sr, MD  more...
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Workup

Laboratory Studies

Laboratory studies may be indicated to rule out other differential diagnoses (eg, metabolic panel including calcium, bone-specific alkaline phosphatase, urine hydroxyproline).

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Imaging Studies

Plain radiography of the skull

Abnormalities have been found in 30%-60% of patients with sphenoid wing meningioma. Hyperostosis, thinning of bone, and irregular foci of calcification can be seen. [70]

CT scanning of the bone window

CT scanning of the bone window typically shows thick, hyperdense, intradiploic lesion expanding the calvaria and destroying the cortical layers of the skull. The bony expansion and ground-glass appearance of sphenoid wing meningioma complicates differentiation from fibrous dysplasia; [71] however, the inner table of the skull looks smooth in fibrous dysplasia, whereas sphenoid wing meningiomas often demonstrate irregularity of the inner table associated with a dural reaction. Clinically, fibrous dysplasia usually presents in younger individuals and stops growing after puberty, in contrast to meningioma, which typically develops in older individuals. Among sphenoid wing meningiomas, 59% are osteoblastic, 10%-35% are osteolytic, and 6% are a mixed picture of both osteolytic and hyperostosis. [67, 72]

CT scan brain bone window showing intraosseous men CT scan brain bone window showing intraosseous meningioma involving left sphenoid wing, lateral orbital, superior orbital fissure, and the anterior part of the middle fossa floor.

MRI

MRI allows better delineation of the soft tissue component of the tumor and dural involvement, as well as delineation of intraorbital extension or growth. There might be no dural tail in sphenoid wing meningioma, especially the en plaque variant. [71]

MRI brain T2W (left) and T1W Fat-Sat (right) seque MRI brain T2W (left) and T1W Fat-Sat (right) sequences showing involvement of the left sphenoid wing associated with dural thickening and the periorbita. Notice proptosis of the left globe secondary to left orbital wall thickening.

Angiography

Angiography is not necessary in sphenoid wing meningioma. When performed, it usually shows tumor blush of the en masse component and tortuous external carotid artery feeders. [71]

C-PiB and F-FDG positron-emission tomography scanning

Two patients who had undergone contrast-enhanced MRI scans that revealed extra-axial tumors next to the sphenoid wing were examined using C-PiB and F-FDG positron-emission tomography (PET) scanning. The researchers concluded that C-PiB could be used as a meningioma marker. [73]  

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Other Tests

Other tests may include the following:

  • Preoperative evaluation of patients with anterior basal meningiomas, including formal visual field and acuity testing.
  • Metastatic work-up, such as CT scanning of the chest, abdomen, and pelvis; skeletal survey; radionucleotide scanning; and PET scanning
  • Intraoperative radiodetection of somatostatin receptors is feasible, especially in bone-invasive meningiomas using gamma probe. [74]
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Histologic Findings

According to the WHO, in 2007 and 2016, 3 types of meningiomas exist based on malignant behavior, as follows: [55, 75, 76]

  • Grade I (benign), with a recurrence rate of 7%-25%, does not meet atypical or malignant meningioma criteria. Despite involvement of the adjacent bony structures, grade I meningiomas do not invade the brain parenchyma. Grade I meningiomas include 9 histological subtypes: meningothelial, fibrous, transitional, psammomatous, angiomatous, macrocystic, secretory, lymphoplasmacyte-rich, and metaplastic.
  • Grade II (atypical), with a recurrence rate of 29%-52%, includes atypical, clear cell, and chordoid histological subtype or increased mitotic activity (4-19 mitoses per 10 high-powered fields) or brain invasion, or three or more of the following features: increased cellularity, small cells with a high nuclear:cytoplasmic ratio, prominent nucleoli, uninterrupted patternless or sheetlike growth, or foci of spontaneous or geographic necrosis.
  • Grade III (malignant), with a recurrence rate of 50%-94%, includes anaplastic, papillary, and rhabdoid histological subtypes. Anaplastic meningiomas have 20 or more mitoses per 10 high-powered fields or malignant characteristics resembling carcinoma, sarcoma, or melanoma.

Malignant transformation is rare. Originally, malignancy was seen in anaplastic tumors, but they may arise from any of the meningioma variants or atypical meningiomas. Papillary histopathology is associated with local aggressiveness and an increased incidence of late distant metastasis. The papillary type is considered malignant by definition and is encountered more frequently in children. [77]

Earlier classification schemes used the term angioblastic meningioma for what is now considered to be a hemangiopericytoma. This neoplasm is distinctly separate from a meningioma, and it shows extremely high propensity for recurrence and metastasis. Hemangiopericytoma is a sarcoma in the new WHO classification. [76, 78]

Meningiomas are generally slow growing. Growth patterns of meningioma in a 2011 series of incidentally diagnosed meningioma included no growth, linear growth, or exponential growth. The presence of calcification, T2-weighted MRI tumor hypointensity, and older age at onset were associated with slower growth rate. [79]

In a large series of 603 asymptomatic meningiomas, 63% did not increase in size, and only 6% of patients eventually experienced symptoms over a mean follow-up of 3.9 years. [80]

Another series of 273 incidental meningiomas in 244 patients with a mean follow-up period of 3.8 years observed a 2 mm or greater increase in maximum diameter in 120 tumors (44% of the cases). [81]

True metastases are extremely uncommon, and dissemination is usually believed to occur hematogenously, with the lungs as the most common site. [82]

Bony invasion is not evidence of malignancy in meningiomas, and invasion of mesenchymal components (eg, bone, muscle, dura) can occur with benign meningiomas. [83]  

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