Approach to brain tumors
From Radipedia
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
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
Metastasis
- 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
Mimics
- 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
Pearls
- Vasogenic edema from tumor, trauma or hemorrhage spares cortex, responds to steroids
- Cytotoxic edema from ischemia or infection affects both gray and white matter
Differentials
Pediatric Infratentorial
- Pilocytic astrocytoma
- Medulloblastoma
- Ependymoma
- Brainstem astrocytoma
Pediatric Supratentorial
- Astrocytoma
- Pleomorphic xanthoastrocytoma
- PNET (Primitive NeuroEctodermal Tumor)
- DNET (Dysembryoplastic Neuroepithial Tumor)
- Ganglioglioma
Adult Infratentorial
- Metastasis
- Hemangioblastoma - uncommon
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