questions 6

Primary Brain Tumors

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Topic updated on 11/01/17 8:11am

Overview
  • Presentation
    • Most common complaints are due to mass effects
      • e.g., seizures, dementia, focal lesions, headache
    • majority of adult primary tumors are supratentorial
    • majority of childhood primary tumors are infratentorial
  • Primary tumor characteristics
    • rarely undergo metastasis
    • usually poorly circumscribed
    • type frequency in adults
      • glioblastoma multiforme > meningioma > ependymoma
    • type frequency in children
      • cystic cerebellar astrocytoma > medulloblastoma > brainstem glioma
    • risk factors
      • NF, cigarette smoking, Turcot's syndrome (colonic polyps and brain tumor)
  • Secondary tumor characteristics
    • 50% of adult brain tumors are due to metastases
    • well circumscribed
    • usually present at gray-white junction 
    • frequency of primary tumor causes
      • lung > breast > melanoma (skin) > kidney > GI
Adult peak-incidence tumors
  • Glioblastoma multiforme
    • type: grade IV astrocytoma
    • prognosis: grave (< 1 year life expectancy)
    • location: cerebral hemispheres
    • stain: GFAP
    • histologic appearance: "psuedopalisading" pleomorphic tumor cells 
      • border central areas of necrosis and hemorrhage
    • gross appearance: can cross corpus callosum (butterfly glioma)
    • note: may arise de novo or progress from a lower grade astrocytoma
  • Meningioma
    • prognosis: resectable
    • location: convexities of hemispheres , parasagittal region, olfactory groove
      • arises from arachnoid cells covering brain
    • histological appearance: spindle cells concentrically arrange in a whorled pattern 
      • psammoma bodies (laminated calcifications)
    • note: more common in women (due to estrogen receptors on tumor cells)
      • associated with neurofibromatosis
  • Schwannoma
    • prognosis: good, resectable
    • location: often localized to CN VIII → acoustic schwannoma
      • usually found at cerebrellopontine angle
      • can present with tinnitus, hearing loss
    • staining: S-100 positive 
    • histologic appearance: biphasic with hypercellular (Antoni A) and hypocellular (Antoni B) areas
    • note: bilateral schwannoma found in neurofibromatosis type 2
  • Oligodendroglioma
    • prognosis: good, slow growing
    • location: most often in frontal lobes
    • histologic appearance: chicken-wire capillary pattern with "fried egg" cells 
      • round nuclei with clear cytoplasm
    • gross appearance: often calcified in frontal lobe
Childhood peak-incidence tumors
  • Pilocytic (low-grade) astrocytoma
    • type: grade I astrocytoma
    • prognosis: benign
    • location: most often infratentorial
      • may be supratentorial (most commonly, craniopharyngioma)
    • stain: GFAP
    • histologic appearance: Rosenthal fibers 
      • eosinophilic corkscrew fibers 
    • gross appearance: cystic + solid, usually well-circumscribed
  • Medulloblastoma
    • most common malignant intracranial tumor of childhood
    • prognosis: poor, highly malignant
      • form of primitive neuroectodermal tumor (PNET)
    • location: cerebellum
      • can compress 4th ventricle → hydrocephalus
    • histologic appearance: rosettes with small blue cells 
    • gross appearance: solid
    • note: radiosensitive
  • Ependymoma
    • prognosis: poor
    • location: most commonly in 4th ventricle
      • can result in hydrocephalus
      • can also arise from cauda equina in adults
    • histologic appearance: characteristic perivascular pseudorosettes 
  • Hemangioblastoma (occurs typically in adults if no genetic predisposition as below)
    • location: cerebellar
    • histologic appearance: foamy cells and high vascularity
    • note: associated with von Hippel-Lindau syndrome when found with retinal angiomas
      • can produce EPO → secondary polycythemia
  • Craniopharyngioma
    • prognosis: benign
    • location: near sella turcica 
      • can present with optic chiasm compression → bitemporal hemianopia
        • confused with pituitary adenoma
      • derived from remnants of Rathke's pouch
    • gross appearance: calcification is common, tooth enamel-like
  • Germinoma
    • prognosis: good
    • location:  pineal gland and suprasellar region
      • derived from nests of embryonic cells arrested during their migration in fetal development
      • Pineal region: Parinaud syndrome (30-40% of cases) compression of tectum causes: paralysis of upward gaze, loss of light perception and accomodation, nystagmus, failure of convergence
      • Suprasellar region: anterior hypopituitarism, precocious puberty, diabetes inspidius, visual disturbances
    • stain: AFP and b-HCG
 


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