An X-ray computed tomography (CT) or magnetic resonance imaging (MRI) scan is necessary to characterize the extent of these tumors (size, location, consistency). CT will usually show distortion of third and lateral ventricles with displacement of anterior and middle cerebral arteries. Histologic analysis is necessary for grading diagnosis. In the first stage of diagnosis the doctor will take a history of symptoms and perform a basic neurological exam, including an eye exam and tests of vision, balance, coordination, and mental status. The doctor will then require a CT scan and MRI of the patient's brain. During a CT scan, X-rays of the patient's brain are taken from many different directions. These are then combined by a computer, producing a cross-sectional image of the brain. For an MRI, the patient relaxes in a tunnel-like instrument while the brain is subjected to changes of magnetic field. An image is produced based on the behavior of the brain's water molecules in response to the magnetic fields. A special dye may be injected into a vein before these scans to provide contrast and make tumors easier to identify. If a tumor is found, a neurosurgeon must perform a biopsy on it. This simply involves the removal of a small amount of tumor tissue, which is then sent to a neuropathologist for examination and grading. The biopsy may take place before surgical removal of the tumor or the sample may be taken during surgery. Grading of the tumor sample is a method of classification that helps the doctor to determine the severity of the<unk>  and to decide on the best treatment options. The neuropathologist grades the tumor by looking for atypical cells, the growth of new blood vessels, and for indicators of cell division called mitotic figures. File:Astrozytom.Low grade<unk>  of the midbrain (lamina tecti), sagittal T1-weighted magnetic resonance imaging after contrast medium administration: The tumor is marked with an arrow. The CSF spaces in front of the tumor are expanded due to compression-induced hydrocephalus internus. Image:Gemistocytic<unk>  003.A pathological specimen of a gemistocytic<unk>  File:MRI Slices - 2007 and 2014 of<unk>  patient - Steven Keating.MRI scans of an<unk>  patient, showing tumor progression over the course of seven years Grading Of numerous grading systems in use for the classification of tumor of the central nervous system, the World Health Organization (WHO) grading system is commonly used for<unk> . Established in 1993 in an effort to eliminate confusion regarding diagnoses, the WHO system established a four-tiered histologic grading guideline for<unk> s that assigns a grade from 1 to 4, with 1 being the least aggressive and 4 being the most aggressive. The WHO grading scheme is based on the appearance of certain characteristics: atypia, mitosis, endothelial proliferation, and necrosis. These features reflect the malignant potential of the tumor in terms of invasion and growth rate. Various types of<unk> s are given these WHO grades: WHO grade<unk> s Description I * Pilocytic<unk>  * Subependymal giant cell<unk>  * Subependymoma Consist of slow-growing<unk> s, benign, and associated with long-term survival. Individuals with very slow-growing tumors where complete surgical removal by stereotactic surgery is possible may experience total remission. Even if the surgeon is not able to remove the entire tumor, it may remain inactive or be successfully treated with radiation. II * Low-grade (fibrillary)<unk>  * Pleomorphic xanthoastrocytoma * Mixed oligoastrocytoma Consist of relatively slow-growing<unk> s, usually considered benign that sometimes evolve into more malignant or as higher grade tumors. They are prevalent in younger people who often present with seizures. Median survival varies with the cell type of the tumor. Grade 2<unk> s are defined as being invasive gliomas, meaning that the tumor cells penetrate into the surrounding normal brain, making a surgical cure more difficult. People with oligodendrogliomas (which might share common cells of origin) have better prognoses than those with mixed oligoastrocytomas, who in turn have better prognoses than patients with (pure) low-grade<unk> s. Other factors which influence survival include age (younger the better) and performance status (ability to perform tasks of daily living). Due to the infiltrative nature of these tumors, recurrences are relatively common. Depending on the patient, radiation or chemotherapy after surgery is an option. Individuals with grade 2<unk>  have a 5-year survival rate of about 34% without treatment and about 70% with radiation therapy. The median survival time is 4 years. III Anaplastic<unk>  Consist of anaplastic<unk> s. It is often related to seizures, neurologic deficits, headaches, or changes in mental status. The standard initial treatment is to remove as much of the tumor as possible without worsening neurologic deficits. Radiation therapy has been shown to prolong survival and is a standard component of treatment. Individuals with grade 3<unk>  have a median survival time of 18 months without treatment (radiation and chemotherapy). There is no proven benefit to adjuvant chemotherapy or supplementing other treatments for this kind of tumor. Although temozolomide is effective for treating recurrent anaplastic<unk> , its role as an adjuvant to radiation therapy has not been fully tested. IV Glioblastoma multiforme (GBM) Consists of Glioblastoma multiforme (GBM), which is the most common and most malignant primary brain tumor. Primary GBM grows and spread to other parts of the brain quickly; they can become very large before producing symptoms, which often begin abruptly with seizures. Less than 10% form more slowly following degeneration of low-grade<unk>  or anaplastic<unk> . These are called secondary GBM and are more common in younger patients (mean age 45 versus 62 years). "Surgical removal remains the mainstay of treatment, provided that unacceptable neurologic injury can be avoided. The extremely infiltrative nature of this tumor makes complete surgical removal impossible. Although radiotherapy rarely cures glioblastoma, studies show that it doubles the median survival of patients, compared to supportive care alone." The prognosis is worst for these grade 4 gliomas. Few patients survive beyond 3 years. Individuals with grade 4<unk>  have a median survival time of 17 weeks without treatment, 30 weeks with radiation, and 37 weeks with surgical removal of most of the tumor followed by radiation therapy. Long-term survival (at least five years) falls well under 3%. According to the WHO data, the lowest grade<unk> s (grade I) make up only 2% of recorded<unk> s, grade II 8%, and the higher grade anaplastic<unk> s (grade III) 20%. The highest graded<unk>  (grade IV GBM) is the most common primary nervous system cancer and second most frequent brain tumor after brain metastasis. Despite the low incidence of<unk> s compared to other human cancers, mortality is significant, as the higher grades (III & IV) present high mortality rates (mainly due to late detection of the neoplasm).
Astrocytoma
Oligoastrocytoma
Hemangiopericytoma
Ameloblastoma
Schwannoma
Glioma
Schwannomatosis
Hemangioblastoma