Approach to brain tumors

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Gliomas - most common

  • Astrocytoma - most common glioma
    • Pilocytic astrocytoma - low grade
    • Anaplastic - intermediate grade
    • Glioblastoma multiforme (GBM) - 50% of astrocytomas, high grade, older age group, can cross midline (butterfly lesion across corpus callosum)
  • Oligodendroglioma
  • Ependymal tumors
    • Ependymoma - likes to squeeze through foramen (Lushka or aquaduct), "plastic" tumor, younger patients
    • Subependymomas - older patients
  • Chorid plexus papilloma and carcinoma - intense enhancement, drop metastasis, hydrocephalus

Meningeal and mesenchymal tumors

  • Meningioma - 90% are typical (benign), hyperdense on CT with avid enhacement, round, sharpley marginated, extra-axial, dural tail, mother in law lesion on angio "comes early and stays late"
  • Hemangiopericytoma
  • Hemangioblastoma - uncommon, a/w VHL, cystic mass with mural nodule

Neuronal and mixed glial/neuronal tumors

  • Gangliogliomas and Ganglioneuroma - cystic, slow growing benign tumors, children and young adults, temporal and frontal lobes, often present with long standing seizures, frequently have calcifications
  • DNET (Dysembryoplastic Neuroepithial Tumor) - cortical based, temporal, present with long stading seizures, bubbly appearance
  • Central neurocytoma - heterogeneous mass arising from septum pellucidum

Germ cell tumors

  • Germinoma - pineal most common, radiation therapy sensitive, 10-30 year olds
  • Teratoma - exclusively in male children

Primitive Neuroectodermal Tumors (PNET)

  • Medulloblastoma - roof of 4th ventricle, agressive, densly packed cells (restricted diffusion)
  • Retinoblastoma
  • Primary cerebral neuroblastoma (supratentorial)
  • Pineoblastoma - highly malignant pineal tumor, peripheral calcifications
  • Ependymoblastoma

Pituitary tumors

Nerve sheath tumors

  • Schwannoma - Benign tumors of crainial or peripheral nerves, multiple a/w NF2
  • Neurofibroma - plexiform neurofibromas of peripheral nerves a/w NF1

Hematopoetic Tumors

  • Lymphoma - hyperdense on CT, can involve corpus calosum and cross midline, responds to seroids and radiation therapy, primary CNS lymphoma a/w AIDS (may be difficult to differentiate from toxoplasmosis)
  • Leukemia

Tumor like

  • Hypothalamic hamartoma - gelatic seizure, floor of 3rd ventricle, iso to GM, no enhancement
  • Lipoma
  • Epidermoid/Dermoid - congenital tumor arising from ectodermal elements in neural tube at closure
    • Epidermoid - squamous epithelium, adults, CSF density on MRI, non-enhacing, restricted diffusion, rare to rupture, CPA most common
    • Dermoid - contain har, sebaceous fat, glands, common in spine, rupture common, younger adults, no enhancement, proteinaceous fluid on MRI


  • Found at the junction of gray and white matter
  • Most are T2 bright and enhance
  • Solitary brain mass has a 50% chance of being metastasis


  • Include: abscess, hematoma, infarct, multiple sclerosis (tumifactive MS has less mass effect than expeted for size, incomplete rim of enhancement), aneurysm, radiation necrosis, herpes encephalitis (restricted diffusion), arachnoid cyst, colloid cyst, etc


  • Vasogenic edema from tumor, trauma or hemorrhage spares cortex, responds to steroids
  • Cytotoxic edema from ischemia or infection affects both gray and white matter


Pediatric Infratentorial

Pediatric Supratentorial

  • Astrocytoma
  • Pleomorphic xanthoastrocytoma
  • PNET (Primitive NeuroEctodermal Tumor)
  • DNET (Dysembryoplastic Neuroepithial Tumor)
  • Ganglioglioma

Adult Infratentorial

Adult Supratentorial

  • Metastasis (50% are solitary)
  • Gliomas
    • Fibrillary astrocytoma
    • Anaplastic astrocytoma
    • GBM
    • Oligodendroglioma

Cerebellar Pontine Angle (CPA) Mass

  • Schwannoma (90%) - only one which expands the IAC (others can invade)
  • Aneurysm, arachnoid cyst
  • Meningioma, metastasis
  • Epidermoid, ependymoma

Pineal tumors

  • Germ cell (>50%) - germinoma, teratoma, etc
  • Pineal cell (25%) - pineoblastoma (malignant), pineocytoma (benign)
  • Glioma

Rim Enhancing Lesions

  • Metastasis
  • Abscess
  • Glioma, granuloma
  • Infarct
  • Contusion

  • Demyelination
  • Resolving hematoma

Common Tumors with Calcifications

  • Oligodendroglioma
  • Ependymoma
  • Craniopharyngioma
  • Choroid plexus tumor
  • Meningioma