•Meningiomas arise from arachnoid cells.

•Their cause is not known but occasionally they arise at sites of trauma or irradiation or in some hereditary tumor diatheses such as neurofibromatosis.

•The tumor grows from arachnoid cells when there has been loss of tumor suppressor genes and activation of protooncogenes.

•Why these changes occur is not known.

•Meningiomas make up 15 - 20% of all intracranial tumors.

•They are more comman in women than men, probably related to their tendency to have estrogen and progesterone receptors.

•They are the only truly benign tumor in that they usually do not recur after complete surgical removal.

•Patients usually have the slow onset of focal neurological signs, occasionally with seizures.

•Complete removal of the tumor is usually curative.

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•Meningiomas have a smooth bosselated external surface which is usually pink-tan in color.

•Cut surface shows a firm, tan tumor mass with fasicles that tend to whorl and stream.

•These tumors may invade the dura but normally do not invade the brain or show necrosis.

•The brain is compressed beneath the tumor.

•Microscopically, meningiomas are made up of plump spindle or polygonal cells which in some areas tend to form lobules, in others, fasicles of cells tend to stream and form small whorls.

•Psammoma bodies (round calcifications) are often present but mitoses and necrosis are uncommon.

• Cotran RS, Kumar V, Robbins SL: Robbins Pathologic Basis of Disease. 5th ed. Philadelphia, W.B. Saunders, 1994, pp.1349-1350.

• Poirer J et.al. Manual of basic neuropathology. Philadelphia: Saunders, 1990, pp.36-40.

• Current literature from PubMed at National Library of Medicine