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Other Primary Neoplasms

1. Meningioma (arises mainly from arachnoid cells; histologically benign)

  • Location:  often parasagittal; attached to dura
  • Signs and symptoms:  often focal, related to location
  • Gross pathology:  irregular, lobulated, well-circumscribed mass; does not invade adjacent brain tissue
  • Microscopic pathology:  several patterns, including whorls or sheets of meningothelial cells, psammoma bodies (concentrically laminated structures produced by mineral deposition in whorls of cells)
  • Incidence:  Meningiomas account for approximately 20% of all primary intracranial neoplasms, and are more common in women
  • Prognosis:  depends on location and accessibility for surgery; after surgery, prognosis is related to completeness of removal
  • Molecular Genetics:   The most common cytogenetic abnormality is loss of chromosome 22, including the region that contains the NF2 gene.

Example of two lobes of a single meningioma. Both regions of the tumor are attached to the meninges, and are very well-circumscribed.  It is more common to see only a single lobe of the tumor, Click to enlarge and also see a MRI of a meningioma in the posterior fossa, a less common location. 
Click here to enlarge
(additional images available)