About 150,000 people are diagnosed with this tumor in the United States.1 Meningiomas are more common in women, with a ratio of 2:1 intracranially and 4:1 in the spine.2
Etiology:
Increasing age and exposure to ionizing radiation; many other environmental, lifestyle, and genetic risk factors have been studied with inconclusive results.1
Signs & Symptoms:
The most common symptoms seen from meningiomas are localized headaches and possibly seizures. The location of the tumor will also display symptoms that are related to functions within that specific area of the brain.3
Diagnostic Procedures:
The most common diagnostic procedures used to diagnose this disease are computed tomography (CT) and magnetic resonance imaging (MRI).3 The CT scan is typically done with and without intravenous (IV) contrast.
Histology:
Six type I lesions, had the more traditional histologic findings of meningothelial cells, they were often found in nests and with psammoma bodies, as well as structures resembling psammoma bodies but lacking calcification.4 Seven more type I lesions, differed from typical type I lesions by being less circumscribed and by having scattered foci of hyperplastic meningothelial cells and psammoma bodies. Three final type I lesions were referred to as rudimentary meningoceles because of the presence of a rudimentary cystic cavity or stalk with nests and strands of meningothelial cells. Type II and III lesions have similar cytologic detail as congenital lesions but usually have less collagen, are more lobulated and cellular, and extend higher into the dermis.
Lymph node drainage:
Meningiomas are located in the brain, therefore no lymph node drainage can occur.4
Metastatic spread:
Intracranial primary neoplasms do not metastasis through the lymphatics. Extracranial true metastasis from primary brain tumors are rare. Peritoneal metastases infrequently occur in patients receiving ventriculoperitoneal shunts to relieve obstructive hydrocephalus from tumors. Some high-grade neoplasms metastasis by "seeding" into the subaracnoid and ventricular spaces and in the spinal canal, particularly with recurrent tumors.5
Grading:
World Health Organization (WHO) 2007 Classification System:5 Grade I: benign Grade II: atypical Grade III: malignant/anaplastic
Staging:
Currently no formal staging system exists for adult meningiomas. CNS tumors are unable to be staged in the same was as other tumors, but TNM system was previously used for brain tumor staging.5
Radiation side effects:
Seizure5
Headache
Short term memory loss
Problem solving difficulty
Secondary tumor
Death
Fatigue
Emesis
Nausea
High tone hearing loss
Vestibular damage
Hormone insufficiency
Blindness
Cataract
Dermatitis
Serous otitis
Prognosis:
The most important prognostic factors are the location, extent of surgical resection, and the WHO grade.5 Benign tumors treated with radiation have 5-year local control rates of 90%. Recurrance after surgery alone is very high, between 50 to 100%. The overall prognosis is good. For patients with malignant tumors that are subtotally resected with radiation, their 5-year progression-free survival is 92% for WHO grades 1 and 2, and slightly less than 50% with WHO grade 3.6
Treatments:
The number one treatment option is normally surgery. Normally is total resection is completed then radiation is not needed. However, if subtotal resection is performed, radiation therapy commonly follows.7 The radiation dose given after subtotal resection is normally 50-55 Gy.3 The GTV is normally defined from a contrast-enhanced MRI. A margin is usually also treated varying from 0.5 to 2.0cm. A common radiation therapy technique is using multiple fields with wedges or rotational fields and using a 3D technique. Radiosurgery is also used.
Fractionated Radiosurgery of a Meningioma8
TD 5/5:
Tolerance dose that within 5 years will cause a minimal 5% complication rate:9 Brain tissue: 45Gy Brainstem: 50 Gy Lens: 10 Gy Optic chiasm: 50 Gy Optic Nerve: 50 Gy Retina: 45 Gy
References:
Mehta MP, Chang SM, Guha A, Newton HB, Vogelbaum MA. Principles and Practice of Neuro-Oncology: A Multidisciplinary Approach. New York, NY: Demos Medical Publishing; 2011.
Bria C, Wegner RE, Clump DA, et al. Fractionated stereotactic radiosurgery for the treatment of meningiomas. J Cancer Res Ther. 2011;7(1):52-57. doi:10.4103/0973-1482.80462.
Type II and III lesions have similar cytologic detail as congenital lesions but usually have less collagen, are more lobulated and cellular, and extend higher into the dermis.
Grade I: benign
Grade II: atypical
Grade III: malignant/anaplastic
Fractionated Radiosurgery of a Meningioma8
Brain tissue: 45Gy
Brainstem: 50 Gy
Lens: 10 Gy
Optic chiasm: 50 Gy
Optic Nerve: 50 Gy
Retina: 45 Gy
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