Low grade glial neoplasm

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Mixed gliomas

Pilocystic astrocytomas

Pleomorphic xanthroastrocytoma

Subependymal giant cell astrocytomas

WHO grades 1 and 2

Asrocytomas Low grade astrocytomas correspond to WHO grade 2 (WHO grade I include pilocytic astrocytomas, Pleomorphic xanthroastrocytoma and Subependymal giant cell astrocytomas

epidemiology: 15% of gliomas in adults 25% of all gliomas of the cerebral hemispheres in children

incidence 1 per 100,000

peak incidence is between ages 30 and 40 (25% of all cases) 60% in males

Location Cerebrum>brainstem>cerebellumFrontal lobe>temporal lobe ' 'Histological Subtypes' ' Fibrillary Astrocytomas: most frequent variant. Gemistocytic Astrocytomas: worse prognosis Protoplasmic: Oligoastrocytomas: more responsive to chemotherapy

Pilocytic Astrocytomas Most common glioma of childhood. Most present in first two decades of life. Typically occur in cerebellum Also: optic nerve, optic chiasm, hypothalamus, basal ganglia, cerebral hemispheres, brainstem (optic nerve pilocytics are associated with NF1) '

Clinical Presentation and Imaging Findings of LGAs Epilepsy in > 50% of cases

CT: nonenhancing, hypodense mass/ if there is enhancement it is typically faint and homogenous MRI: Low intensity on T1, increase signal on T2 (homogenous)Enhancement sometimes (8-15% of cases) PET: low grade areas show up as cold/hypometabolic areas/ high grade reas will show up as hot/hypermetabolic areas

Prognostic Factors

Median survival 6-8 years

Seizure, gross total resection, presentation at young age correlate with better prognosis Worse prognosis: tumor volume, higher mitotic activity, Tumor and biological Markers: Tumor volume predicts disease free survival Cell Proliferation Markers: Worse prognosis with Higher mitotic activity BUdR labeling index greater than 8% MIB-1 labeling index greater than 8% P53 (tumor suppressor gene): mutations are common in astrocytomas

ProgressionCause of death in majority of patients with LGA is progression Median survival 7.5 years5 year survival 65%10 year survival 40%

Pleomorphic Xanthoastrocytomas Typically children and young adults with epilepsy. Often superficial. Affect temporal lobe in 50% of cases. Can affect spinal cord, cerebellum, and retina. Typically there is leptomeningeal involvement. WHO grade I

Good prognosis Tx: resection/ no chemo or XRT Can progress

Subependymal Giant Cell Astrocytomas; Occur almost exclusively in the setting of Tuberous Sclerosis. Occur in 10% of cases with Tuberous sclerosis Genereally in first 2 decades of life

WHO grade I

Usually in area of Foramen of Monro Sxs: hydro/ seizures Resection: trasncortical or transcallosal Before resection evaluate for cardiac anomalies ''''

Oligodendrogliomas Predilection for frontal lobesPositive for calcifications (gyriform/ ribbonlike)Fried egg appearance on microscopy Peak incidence around age 40 and a smaller peak around age 10 Seizures are presenting symptom in 50% to 80% of cases Path: WHO grade 2: oligodendrogliomaWHO grade 3: anaplastic oligodendroglioma Can progress to GBM Prognosis: P53 staining implies worse prognosis. Prognosis better than for LGA’sMayo series: median survival: 7.1 years TX: PCV most widely used: procarbazine, lomustine, vincristine. Low dose temozolamide also being used currently.

'Mixed Gliomas Most common is oligoastrocytoma (WHO grade 2)Prognosis: ?Imaging and presentation is similar to oligodendrogliomaMedian survival 6.3 yearsRespond to chemoPrognosis is probably between LGAs and oligodendroglioma. Chemosenstivity is proportional to ratio of oligiodendroglioma to astrocytoma '

Gangliogliomas' UncommonOccur throughut neuroaxisBenignOccur in children and young adultsMixture of neuronal and glial cellsMost common in temporal and frontal lobes May be solid or cysticCT isodense or hypoodense with poor contrast enhancementMRI: hypodense relative to gray matter on T1 and hyperdense relative to gray matter on T2Usually enhance with gad Macroscopically: they are firm, Occur in young adults

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