Meningiomas (Tumors of the Meninges)

Comprise about 25% to 30% of primary intracranial tumors

Incidental finding 1.4% at autopsy

All age groups affected; most common in middle-aged to elderly patients; peak in fifth to seventh decades

More common in females (F : M ratio ranges from 2 : 1 to 3 : 1); F : M ratio is 10 : 1 for spinal cord meningiomas

Usually sporadic; multiple in about 10% of cases

May arise secondary to radiation exposure; both low dose and high dose

Multiple meningiomas may arise with neurofibromatosis type 2 (NF2)

Chromosomal abnormalities include deletion of chromosome 22

Slow-growing tumors; symptoms result from location and compression of adjacent structures; headache and seizures are the most common presenting symptoms

Most commonly found in intracranial, intraspinal, or orbital locations

Intracranial locations: cerebral convexities (50% along sagittal sinus), olfactory grooves, parasellar/suprasellar, petrous ridges, sphenoid ridges, tentorium, posterior fossa

Rarely located in intraventricular or epidural spaces

Extra-axial, intradural location most common in spinal cord

Most meningiomas are WHO Grade I and are generally treated by gross total resection; may recur if not complete excised

Radiation therapy or radiosurgery may be used for recurrent tumors or for small tumors in surgically inaccessible areas (i.e., cavernous sinus)

MRI typically shows a circumscribed, isodense, contrast-enhancing, dural-based mass with classic “dural tail” sign (enhancement of dura adjacent to tumor)

May have peritumoral edema resulting from vascular compromise

CT scan may demonstrate tumor calcification or bone formation

Well-demarcated, firm, rubbery, yellow-tan, round to lobulated mass attached to dura

Usually compresses adjacent brain or spinal cord

May invade skull and cause hyperostosis (thickening of the cortical bone)

General features of the most common meningothelial variant:

• Lobules of mostly uniform cells arranged in a syncytium

• Meningothelial whorls and psammoma bodies are classic

• Bland, oval nuclei, and fine chromatin that may demonstrate central clearing

• May have nuclear pseudoinclusions

• Many variants exhibit a wide range of morphologic appearances (see the next three topics)

Immunoreactive for vimentin and epithelial membrane antigen (EMA)

S-100 variably reactive but usually not prominent

Progesterone receptor expressed in about 60% of cases (most often in women)

Metastatic carcinoma

Schwannoma

Solitary fibrous tumor

Sarcoma

Similar to meningothelial variant

General symptoms result from location and compression of adjacent structures

Headache and seizures are the most common presenting symptoms

Psammomatous meningiomas are typically found in thoracic spinal region of middle-aged women

Surgical excision in most cases