Meningioma

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Meningioma
AxialMeningioma.jpg
Axial T1 MRI with contrast of left fronto-temporal meningioma
Tumor Class Meningioma
Cell of origin Arachnoid Meningothelial Cell
WHO Grade I for most, II includes clear cell and chordoid, III includes papillary and rhabdoid
Survival Variable
Treatment Surgery, Radiation
Histologic Features
Gross Flesh colored tumor with variable vascular proliferation and calcium
Micro Variable depending on histologic subtypes (often see psammoma bodies)
Radiographic Features
MRI Homogenously enhancing mass which appears extraaxial and may have dural tail (nonspecific). Often with associated edema appreciated on T2 or FLAIR.
CT hyperdense lesion with associated hypodense adema.


Contents

Definition

Meningiomas are generally benign tumors that arise from an arachnoid meningothelial cell (also referred to as an arachnoid cap cell). They are usually extra-axial tumors that compress the brain. They can arise from virtually any part of meningeal covering. They can grow extracranially as well through the skull and are known as Intraosseous Meningiomas.

Epidemiology

More common in females; common in neurofibromatosis type II, previous radiotherapy and estrogen dependent neoplasms such as breast carcinoma and endometrial carcinoma

Histologic Subtypes

Types of meningiomas – no prognostic significance is attached to any one of these

  1. meningothelial – sheets of oval cells with prominent small nucleoli, rudimentary whorls, and fibrous capsule
  2. fibrous – spindle shaped, elongated cells associated with variable amounts of pericellular collagen
  3. transitional – contain whorls and cord of neoplastic cells
  4. psammomatous, angiomatous (strikingly prominent blood vessels), microcystic (many cystic spaces), secretory (with many eosinophilic globules), clear cell (groups of clear cells divided by fibrous septae), choroids, lymphoplasmacyte, metasplatic
  5. atypical (containing foci of micronecrosis with no whorls or lobules), papillary (found in young patients, aggressive, high frequency of metastasis) and anaplastic (large areas of necrosis and marked cellular pleomorphism) meningioma are other classes of meningiomas

Genetic Characteristics

More than 75% of meningiomas express progesterone receptors Monosomy of chromosome 22 is the most common cytogenetic abnormality in meningiomas

Surgical Treatment

Simpson grading system for removal of meningiomas – most important predictor of recurrence of meningioma is postoperative tumor residual I – macroscopically complete removal with excision of dural attachment and removal of overlying bone II – macroscopically complete removal with heat coagulation of dural attachment III – macroscopically complete removal without heat coaguation of dural attachment or the overlying bone IV – partial removal of the tumor in situ V – biopsy

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