Neurosurgical Atlas Flashcards
Basic description of pilocytic astrocytomas.
- Slow growing, well circumscribed tumor arising from astrocytic precursors.
- Most common pediatric primary intracranial neoplasm.
Pathology of pilocytic astrocytomas.
- Biphasic pattern of astrocytes (Rosenthal fibers and multipolar cells).
- Syndromic or sporadic (optic nerve/chiasm PAs associated with NF1).
CT findings of pilocytic astrocytomas.
- Mixed solid-cystic mass with minimal surrounding edema.
- May have calcification.
- Strong mural nodular enhancement, non-enhancing cystic component.
T1WC+C findings of pilocytic astrocytomas.
- Enhancing solid component with/without cyst wall enhancement.
Basic description of pleomorphic xanthoastrocytoma.
- Supratentorial cortical/peripheral astrocytic tumor.
Pathology of pleomorphic xanthoastrocytoma.
- Astrocyte pleomorphism and lipid-containing cells.
2. May show anaplastic features (10-15%).
General imaging features of pleomorphic xanthoastroctyoma.
- Temporal lobe > frontoparietal > occipital.
- Classically cystic with solid mural nodule, often abuts pial surface.
- May have enhancing dural tail of leptomeningeal attachment.
CT findings of pleomorphic xanthoastrocytoma.
- Hypodense cystic component.
2. Minimal to moderate adjacent edema.
T1WC + C findings of pleomorphic xanthoastrocytoma.
- Generally strong enhancement, sometimes enhancing dural tail/leptomeninges.
Basic description of anaplastic astrocytoma.
Infiltrating malignant astrocytoma with ill-defined tumor margins and extensive edema.
Pathology of anaplastic astrocytoma.
- Usually develops from malignant degeneration of low-grade astrocytoma.
- Commonly dedifferentiates into GMB (-50%) within 2 years.
- Focal or diffuse anaplasia, highly proliferative.
- Increased cellularity and nuclear atypia, usually no necrosis or microvascular proliferation.
General imaging characteristics of anaplastic astrocytoma.
- Ill-defined, infiltrating white matter mass.
- Location in frontal and temporal lobes most common, brainstem and spinal cord uncommon.
- Spreads along white matter tracts, but may spread via CSF, leptomeninges, and ependymal.
CT findings of anaplastic astrocytoma.
- Hypodense, ill-defined white matter mass.
2. Usually does not enhance on contrast-enhanced CT.
Basic description of GBM.
- Malignant, rapidly enlarging astrocytic tumor with microvascular proliferation and necrosis.
- Most common primary intracranial neoplasm.
Pathology of GBM.
- Necrosis and microvascular proliferation are characteristic features.
- Develops do novo (primary) or from malignant dedifferentiation of AA (secondary).
- Associated with NF-1, Turcot, Li-Fraumeni, and Maffuci syndromes.
Clinical features of GBM.
- Median survival < 1 year (better prognosis with younger age, greater resection, and MGMT-positive genetics).
CT features of GBM.
- Irregular hypo-to isodense mass with central hypodensity (necrosis).
- Surrounding vasogenic edema.
- Irregular, heterogenous ring of enhancement on contrast-enhanced CT.
T1WI of GBM.
- Irregular, hypointense white matter mass, areas of hyperintensity may represent subacute hemorrhage.
T2WI of GBM.
- Heterogeneously hyperintense, surrounding vasogenic edema, presence of flow voids suggests neovasculatiry.
T1WI+C of GBM.
- Thick, irregular ring of peripheral enhancement.
2. Enhancement may be ring, nodular, homogenous or patchy.
MRS of GBM.
- Decreased NAA and myoinositol.
- Increased choline, lipid/lactate peak indicating anaerobic metabolism of necrosis.
- Increased relative CBV compared with lower grade astrocytomas.
Pathology of posterior fossa ependymoma.
- 3 histological subtypes (PF-ependymoma, PF-ependymoma type A, PF ependymoma type B).
- Subtype A highly malignant.
General imaging features of posterior fossa ependymoma.
- Well-marginated, lobulated mass.
- Majority arise within 4th ventricle and extend through/widen ventricular foramina into adjacent parenchymal and basal cisterns.
- Displaces rather than invades adjacent parenchyma.
CT of posterior fossa ependymoma.
- Lobulated, often calcified mass arising within inferior portion of 4th ventricle.
T1WI of posterior fossa ependymoma.
- Heterogeneous, often hypointense, areas of calcification and hemorrhage appear hyperintense.
T1WI+C of posterior fossa ependymoma.
- Variable enhancement.
MRS of posterior fossa ependymoma.
- Elevated choline and lactate.
- Decreased NAA.
- MRS not generally helpful in distinguishing between posterior fossa medulloblastomas and astrocytomas.
Basic description of supratentorial ependymomas.
- Hemispheric glial-cell tumor arising from ependymal cells.
- Extraventricular subependymomas may arise from fetal ependymal rests.
Pathology of supratentorial ependymomas.
- WHO I: myxopapillary ependymoma (more often occurring at the conus medulluaris).
- WHO II: cellular, papillary, clear cell, and tanycytic variants.
- WHO III: most common in adults, trisomy 19 and anaplastic variants.
Histology of supratentorial ependymomas.
- Perivascular and ependymal rosettes.
Imaging features of supratentorial ependymomas.
- Heterogeneous, mixed solid-cystic supratentorial mass.
- Often large at presentation (>4cm).
- Majority are extraventricular.
- 3rd ventricle most common intraventricular location.
CT imaging of supratentorial ependymomas.
- Heterogeneously iso-to hypodense.
2. Calcification common.
T2*/GRE/SWI of supratentorial ependymomas.
- Black signal blooming secondary to calcification and/or hemosiderin deposition from blood products.
Pathology of oligodendrogliomas.
- Arises from malignant transformation of mature oligodendrocytes or glial precursor cells.
- Calcification and cystic degeneration common.
- “Fried egg” appearance due to rounded nuclei and clear cytoplasm.
- Associated with IDH1 or MGMT positive genetics.
General imaging features of oligodendrogliomas.
- Usually supratentorial location (frontal lobe»_space; temporal, parietal, and occipital lobes).
- Calcification present in 40-80%.
- Usually minimal to no peritumoral edema.
MRS of oligodendrogliomas.
- elevated choline, decreased NAA, absent lipid/lactate peak (unlike anaplastic oligodendroglioma).
- Unique characteristic of elevated relative CBV in spite of lower grade due to pathologic feature of “chicken-wire vascularity”.
Pathology of atypical/malignant meningiomas.
- WHO grade II (atypical) and WHO grade III (malignant).
- Most likely arise from dedifferentiation of traditional meningiomas.
- Increased mitoses, nucleus-to-cytoplasm ratio, necrosis, and nuclear atypia compared to traditional meningioma’s.
General imaging features of atypical/malignant meningiomas.
- Dural based, extra-axial mass with necrosis, invasion of adjacent brain, and extensive peritumoral brain edema.
- May arise within any location in the neuraxis. (AMs: CPA cistern, tentorium most common; MM: parasagittal or cerebral convexity).
CT findings of atypical/malignant meningiomas.
- Ill-defined, hyperdense mass extending intra-and extra cranially.
- Minimal calcification compared to traditional meningiomas.
- Extensive hypodense peritumoral edema.
- Avid enhancement on contrast-enhanced CT.
FLAIR imaging of atypical/malignant meningiomas.
- often marked hyperintense peritumoral edema.
T1WI+C of atypical/malignant meningiomas.
- Avid enhancement with enhancing margins invading adjacent structures.
DWI of atypical/malignant meningiomas.
- Reduced diffusivity (bright DWI, dark ADC).
Basic description of craniopharyngiomas.
- Benign tumor arising from Rathke pouch epithelium.
2. Most common pediatric nonglial-origin tumor.
Pathology of craniopharyngiomas.
- Two histological types (adamantinomatous - partially cystic mass in children, papillary - solid mass in adults).
- Cysts with viscous “crankcase oil” or “motor oil” contents.
Age distribution of craniopharyngiomas.
- Adamantinomatous - ages 5-15 years.
2. Papillary - > 50 years.
General imaging features of craniopharyngiomas.
- Multilobulated or multicystic mass.
- Location may be suprasellar, supra and intrasella, or completely intrasellar.
- Adamantinomatous - mixed solid-cystic or predominantly cystic.
- Papillary - predominantly solid.
CT of adamantinomatous craniopharyngiomas.
- Cystic components are hypodense, solid components are isodense.
- 90% with calcifications.
- 90% enhance (nodule or rim enhancement).
CT of papillary craniopharyngiomas.
- Isodense solid tumor.
2. Calcification much more rate.
T1WI of craniopharyngiomas.
- Often hyperintense due to proteinaceous material.
2. Isointense or heterogenous solid tumor component.
T1WI+C of craniopharyngiomas.
- Enhancement of cyst wall and solid tumor components.
Basic description of vestibular schwannomas.
- Benign peripheral nerve sheath tumor arising from Schwann cells of CN 8 (vestibular portion) within the CPA-IAC.
Pathology of vestibular schwannomas.
- CN 8 superior vestibular branch > inferior branch.
2. Variable hpercellular (Antoni A) and more hypocellular (Antoni B) areas are characteristic.
General imaging features of vestibular schwannomas.
- Well-marginated, enhancing mass within the CPA or CPA-IAC with “ice cream on cone” morphology.
- Expansion of the IAC (in contrast to meningiomas).
- Calcification, cystic degeneration may be seen.
T2WI of vestibular schwannomas.
- High resolution sequences (SPACE, CISS, or FIESTA) optimize visualization.
- Appears as a hypo-to isointense CPA-IAC filling defect.
Basic description of pineocytomas.
- Slow-growing pineal parenchymal tumor.
Pathology of pineocytomas.
- Arises from pineocytes or pineocyte precursors.
- Well-differentiated tumor without mitoses or necrosis.
- Small, uniform cells arranged in sheets with intervening septae are typical microscopic features.
General features of pineocytomas.
- Peripherall-calcified, well circumscribed pineal region mass.
- Calcifications and cysts are often present.
- Rare intraventricular extension, CSF dissemination or parenchymal invasion.
CT findings of pineocytomas.
- Well-circumscribed, iso to hypodense pineal mass.
2. +/- peripheral calcification.
Basic description of pineoblastomas.
- Malignant, invasive pineal parenchymal tumor arising from embyronic pineocyte precursors (PNET).
Pathology of pineoblastomas.
- Invades adjacent structures often including the cerebral aqueduct.
- CSF dissemination common.
- Hypercellularity and increased mitoses are characteristic features.
- Associated with germline DICER1 mutations (DICER! syndrome) and RB1 (bilateral retinoblastomas and pineoblastoma).
General imaging features of pineoblastoma.
- Lobulated, poorly marginated pineal mass.
- Often larger and more invasive than pineocytomas.
- Peripheral (“exploded”) calcifications common.
- Commonly invades adjacent structures including cerebral aqueduct, corpus callosum, thalamus, brainstem and vermis.
- May see superior displacement of cerebral veins and mass effect on the tectum.
CT findings of pineoblastoma.
- Heterogenous density, irregular pineal mass.
2. Peripheral calcification.
T1WI+C of pineoblastoma.
- Heterogenous enhancement.
MRS of pineoblastoma.
- Elevated choline.
2. Decreased NAA.
Basic description of germinoma.
- Intracranial germ cell tumor often occurring in the pineal region.
Pathology of germinoma.
- WHO grade II(pure germinoma) or grade III (syncytiophoblastic giant cells).
- Associated with Down’s, Klinefelter, and NF-1 syndromes.
- Polygonal primitive germ cells and lymphocytic infiltrates are common microscopic features.
Gender predilection for germinomas.
- Marked male gender predilection in pineal region germinomas.
- Females more commonly afflicted with suprasellar germinomas.
Lab findings for germinomas.
- Increased serum/CSF B-hcg.
CT findings for germinomas.
- Lobulated, hyperdense mass.
- +/- cysts, hemorrhage.
- Avid, homogeneous enhancement on contrast enhanced CT +/- CSF dissemination.
T1WI of germinomas.
- Iso to hyperintense.
2. Normal posterior pituitary “bright spot” may be absent in suprasellar germinoma.
DWI of germinomas.
- Diffusion restriction due to hypercellularity.
T1WI+C of germinomas.
- Avid, homogeneous enhancement including areas of CSF dissemination and parenchymal invasion.
MRS of germinomas.
- Elevated choline.
2. Decreased NAA.
Basic description of teratomas.
- Midline intracranial tumor arising from mulitpotential germ cells.
Pathology of teratomas.
- Contains tissue from all germ cell types: ecto, meso and endoderm.
- Three types:
Mature - well differentiated, WHO grade 1, often with cystic tumor component.
Immature - intermediate differentiation.
Malignant - malignant degeneration of immature teratoma, may contain somatic tumors.
Clinical features of teratomas.
- Arises during fetal development due to aberrant formation of the primitive streak.
- Mean patient age at diagnosis is 15 years.
- Majority are lethal in utero or during 1st week of life.
Lab findings for teratomas.
- Increased serum CEA +/- alpha fetoprotein.
CT findings of teratomas.
- Heterogeneous and containing very low density fat, hyperdense calcification, intermediate density soft tissue, and low-density cysts.
T1WI of teratomas.
- Heterogeneous hyperintensity due to fatty components and calcification.
Basic description of arachnoid cysts.
- Intracranial, extra-axial, CSF containing cysts without communication with the ventricular system.
Pathology of arachnoid cysts.
- Originates from embryonic meninges that fail to fuse during Sylvian fissure development.
- CSF contents may arise from unidirectional inflow (ball-valve mechanism) vs secretion by cells lining AC wall.
- Rare association with Aicardi and Pallister-Hall syndromes.
- Associated with temporal lobe hypoplasia, subdural hematomas, foramen of Monro/aqueductal stenosis.
General imaging features of arachnoid cysts.
- Well-marginated extra-axial cyst which follows CSF density/signal intensity.
- Mass effect and displacement of adjacent cortex.
Common locations for arachnoid cysts.
- Middle cranial fossa»_space; CPA, suprasellar cisterns.
DWI of arachnoid cysts.
- No diffusion restriction.
Basic description of AT/RTs.
- Aggressive, infiltrative pediatric rhabdoid tumor with highly variable appearance and histology.
Pathology of AT/RTs.
- WHO grade IV.
- Involves mesenchymal, neuronal, glial, and epithelial cell lines (“teratoid”).
- Mutations of SMARCB1/hSNF5 and loss of INI1 protein is diagnostic of AT/RT.
Clinical features of AT/RTs.
- Most commonly affects children < 3 years and usually in the posterior fossa.
- No gender predilection.
- Treatment involves resection +/- adjuvant chemoradiation.
- Overall 5-year survival < 30%.
General imaging features of AT/RTs.
- Highly variable, nonspecific morphology and imaging characteristics.
- Mixed solid-cystic mass.
- +/- calcification, hemorrhage, and necrosis.
- Leptomeningeal/CSF dissemination common (>30%).
CT findings of AT/RTs.
- Hyperdense mass.
2. Hyperdense calcification and hemorrhage or hypodense cysts may be seen.
MRI findings of AT/RTs.
- Heterogenous signals due to cystic or hemorrhagic components.
DWI for AT/RTs.
- Demonstrates restricted diffusion in hypercellulr regions of tumor.
MRS of AT/RTs.
- Elevated choline.
- Decreased NAA.
- +/- lactate/lipid peaks.
Basic description of carotid body glomus tumor (carotid body paraganglioma).
- Benign, hypervascular neuroendocrine tumor of neural crest origin.
Pathology of carotid body glomus tumor (carotid body paraganglioma).
- Glomus caroticum arise from glomus bodies within the carotid body at the carotid bifurcation.
- Composed of chemoreceptor cells of neural crest origin.
- Arterial supply from ascending pharyngeal.
- Associated with NF-1, MEN-2, and VHL.
- Chief cells rests (zellballen) and sustentacular cells within fibromuscular stroma are characteristic microscopic features.
Clinical features of carotid body glomus tumor (carotid body paraganglioma).
- Pulsatile, painless mass at the angle of the mandible with gradual enlargement.
- CN X and XII neuropathies.
Treatment of carotid body glomus tumor (carotid body paraganglioma).
- Surgical resection based on Shamblin classification: tumor size and degree of contact with ICA.
- Higher classification predicts surgical morbidity (CN neuropathy).
General imaging features of carotid body glomus tumor (carotid body paraganglioma).
- Lobulated, enhancing mass centered within the carotid bifurcation.
Basic description of central neurocytoma.
- Well-marginated, usually benign intraventricular neuroepithelial tumor.
Pathology of central neurocytoma.
- WHO grade II.
- Round cells with stippled nuclei are characteristic microscopic features.
- Synaptophysin positive.
General imaging findings of central neurocytoma.
- Supratentorial, intraventricular mass with cystic or bubbly appearance.
- Often located with lateral ventral frontal horn or body near the foramen of Monro.
- Frequently shows calcification.
CT findings of central neurocytoma.
- Heterogeneous density intraventricular mass due to solid and cystic components.
T1WI+C of central neurocytoma.
- Heterogenous enhancement.
MRS of central neurocytoma.
- Increased choline.
- Decreased NAA.
- Glycine peak at 3.55.
Basic description of choroid plexus carcinoma.
- Malignant, rapidly growing intraventricular tumor arising from choroid plexus epithelium.
Pathology of choroid plexus carcinoma.
- Hypercellularity, pleomorphism, and increased mitosis are characteristic microscopic features.
- Increased Ki-67 index.
- Hemorrhage, cysts, calcification and necrosis are common.
- Invasion of adjacent ependyma.
- High association with SV40 virus.
- Associated with Li-Fraumeni and Aicardi syndromes.
General imaging features of choroid plexus carcinoma.
- lobulated or irregular, enhancing intraventricular mass with ependymal invasion.
- Lateral ventricle was complication.
CT findings for choroid plexus carcinoma.
- Iso to hyperdense.
2. +/- Calcification.
FLAIR imaging of choroid plexus carcinoma.
- Heterogeneous signal intensity, periventricular bright signal suggests invasion and/or transependymal CSF flow from hydrocephalus.
MRS of choroid plexus carcinoma.
- Elevated choline.
- Elevated lactate.
- Absent NAA.
Basic description of choroid plexus papilloma.
- Benign, lobulated, intraventricular mass arising from choroid plexus epithelium.
- Made disseminate via CSF.
Pathology of choroid plexus papilloma.
- Fibrovascular connective tissue covered by cuboidal or columnar choroid plexus epithelium.
- WHO grade 1 (typical CPP) or II (atypical CPP).
- Cysts and hemorrhage may be seen.
- Rare necrosis or invasion of adjacent brain parenchyma.
- Associated with Li-Fraumeni and Aicardi syndromes.
- Associated with SV40 infection.
Clinical features of choroid plexus papilloma.
- Usually arising in lateral or 4th ventricles.
- Lateral ventricle: majority of cases < 20 years old.
- 4th ventricle: adults more commonly affected.
General imaging features of choroid plexus papilloma.
- Lobulated, frond-like, and avidly enhancing intraventricular mass.
- Arising in regions of choroid plexus.
- Lateral ventricle atrium or trigone > foramen of Luschka or posterior medullary velum of 4th ventricle > 3rd ventricular roof.
- Hemorrhage and calcification common.
T1WI+C findings of choroid plexus papilloma.
- Avid, homogenous enhancement most common.
Basic description of colloid cysts.
- Mucin-containing, unilocular third ventricular cyst often located near the foramen of Monro.
- Synonymous terms: paraphyseal or neuroendodermal cyst.
Pathology of colloid cysts.
- Congenital abnormality due to ependymal encystment or persistence of the paraphysis.
- Thin fibrous capsule of simple or pseudostratified epithelium with goblet and ciliated cells.
- Center filled with mucin, cholesterol, and desquamated epithelium.
General imaging features of colloid cysts.
- Well-marginated hyperdense unilocular cyst arising within anterior third ventricle near the foramen on Monro.
- Forniceal pillars elevated over cyst.
CT findings of colloid cysts.
- Majority are hyperdense due to high proteinaceous content.
T1WI of colloid cysts.
- Iso to hyperintense due to cholesterol content.
T1WI + C of colloid cysts.
- No enhancement.
Basic description of dysplastic cerebellar gangliocytoma.
- AKA Lhermitte-Duclos, the neurologic manifestation of multiple hamartoma and neoplasia syndrome or Cowden syndrome.
- Benign cerebellar lesion of uncertain etiology.
Pathology of dysplastic cerebellar gangliocytoma.
- Benign cerebellar mass with thickened, irregular cerebellar folia.
- Pathogenesis unclear: hamartomatous, neoplastic, or congenital.
- WHO grade I.
- No malignant potential.
Microscopic features of dysplastic cerebellar gangliocytoma.
- Absence of cerebellar Purkinje cells, abnormal ganglion cells, and hypertrophic granule cell layer.
General imaging features of dysplastic cerebellar gangliocytoma.
- “Corduroy”, striated, or tigroid appearance of cerebellar hemisphere due to thickened, irregular folia.
- Most commonly unilateral cerebellar hemisphere involvement +/- vermis.
CT findings of dysplastic cerebellar gangliocytoma.
- iso to hyperdense lesion with thickened, irregular, and tigroid folia.
MRS of dysplastic cerebellar gangliocytoma.
- Decreased NAA.
- Decreased choline.
- Decreased MI.
MR perfusion of dysplastic cerebellar gangliocytoma.
- Increased relative blood volume.
2. Increased relative cerebral blood flow may be present.
Basic description of epidermoid cyst.
- Benign, ectodermal inclusion cysts of congenital or acquired etiology.
Pathology of epidermoid cyst.
- Congenital: arise from ectodermal epithelium in the 3rd-5th weeks of embryogenesis during the process of neural tube closure.
- Rare acquired lesions are thought to be post-traumatic in etiology, often spinal in location when secondary to LPs.
- Gross pathologic features include shiny or “pearly” appearance within an outer connective tissue wall.
- Cysts contain solid cholesterol crystals and keratin.
General imaging features of epidermoid cyst.
- Most cases (90%) are intradural and located within the basal cisterns (CPA, 4th ventricle, parasellar).
- Minority of cases (10%) are extradural and may arise within the bony calvarium or spine.
CT findings of epidermoid cyst.
- Well-defined, usually hypodense mass similar in density to CSF.
T1WI of epidermoid cyst.
- Signal intensity typically greater than CSF, but less than brain parenchyma.
T1WI + C of epidermoid cyst.
- Typically non-enhancing.
DWI of epidermoid cyst.
- Demonstrates often markedly increased signal (restricts) with corresponding ADC value near that of brain parenchyma (in contrast to an arachnoid cyst which will not restrict).
Basic description of ganglioglioma.
- Slow-growing, well-differentiated, and cortically based neuroglial tumor.
Pathology of ganglioglioma.
- WHO grade I or II.
- Anaplastic gangliogliomia (WHO III) rare.
- Dysmorphic ganglion and glial cells.
Clinical features of ganglioglioma.
- Most common tumor-related cause of temporal lobe epilepsy.
- Associated with NF-1, NF-2, and Turcot syndrome.
General imaging features of ganglioglioma.
- Mixed solid-cystic, enhancing, and cortically based (cyst with mural nodule).
- Temporal lobe»_space; frontal and parietal lobes.
- Associated with adjacent cortical dysplasia, expansion of adjacent cortex.
CT findings of ganglioglioma.
- Variable density and enhancement on contrast enhanced CT.
2. Calcification commonly present, hemorrhage rare.
T1WI of ganglioglioma.
- Iso to hypointense relative to gray matter, +/- cortical dysplasia.
T2WI of ganglioglioma.
- Usually hyperintense or heterogeneous, lacks adjacent edema.
T1WI + C of ganglioglioma.
- Moderate, heterogeneous enhancement or non-enhancing.
Basic description of glomus jugulare paraganglioma.
- Benign, neuroendocrine tumor of neural crest origin arising near the jugular foramen.
Pathology of glomus jugulare paraganglioma.
- Arises from glomus bodies which function as chemoreceptors.
- Located within jugular bulb, CN IX tympanic branch, and CN X auricular branch.
- Classically spreads through the middle ear in a superior-lateral vector (may involve CN VII mastoid segment).
- Arterial supply from the ascending pharyngeal artery.
- Associated with MEN-1, NF-1 and multiple myocutaneous neuromas.
- Patients are at increased risk of thyroid malignancy.
Clinical features of glomus jugulare paraganglioma.
- Pulsatile tinnitus.
2. CN neuropathies (9-12).
General imaging features of glomus jugulare paraganglioma.
- Lobulated solid mass of variable size.
- Hallmark “salt and pepper” MRI appearance.
- Involvement of middle ear common, may invade jugular vein or sigmoid sinus.
CT findings of glomus jugulare paraganglioma.
- Soft tissue mass centered near the jugular foramen.
2. +/- adjacent permeative-destructive bony changes.
T1WI findings of glomus jugulare paraganglioma.
- Hyperintense “salt” due subacute hemorrhage, hypointense “pepper” due to arterial flow voids.
T11WI+C of glomus jugulare paraganglioma.
- Avid enhancement.
MRV of glomus jugulare paraganglioma.
- May show jugular vein and/or sigmoid sinus involvement/occlusion.
PET/CT of glomus jugulare paraganglioma.
- Avid FDG uptake which may be useful in metastatic evaluation or evaluating treatment response.
Basic description of glomus vagale paraganglioma.
- Benign, hypervascular neuroendocrine tumor of neural crest origin.
- Less common than glomus caroticum (carotid body tumor) and glomus jugulare.
Pathology of glomus vagale paraganglioma.
- Arises from glomus bodies within CN X nodose ganglion.
- Composed of chemoreceptor cells of neural crest origin.
- Arterial supply from the ascending pharyngeal artery.
- Chief cells rests (zellballen) within fibromuscular stroma are characteristic microscopic features.
Clinical features of glomus vagale paraganglioma.
- Pulsatile, painless lateral neck mass.
2. CN IX-XII neuropathies.
General imaging features of glomus vagale paraganglioma.
- Lobulated, enhancing mass centered within the nasopharyngeal/suprahyoid carotid space about 2cm below the jugular foramen.
- Displaces the ICA anteromedially, jugular vein posterolaterally, and parapharyngeal fat anterolaterally.
- Hallmark “salt and pepper” MRI appearance.
Basic description of hemangioblastoma.
- Usually benign, vascular, and slow-growing adult cerebellar tumor.
Pathology of hemangioblastoma.
- WHO grade I.
- Well-circumscribed, highly vascular mass composed of stromal cells and small blood vessels.
- Associated with VHL (up to 40% of all hemangioblastomas are in patients with VHL).
- Often multiple, including retinal hemangioblastoma.
General imaging features of hemangioblastoma.
- Posterior fossa mass (supratentorial and retinal HGBLs in VHL patients).
- Cyst with enhancing mural nodule common morphology but sometimes solid withotu cyst.
- May have surrounding edema, particularly in the setting of hemorrhage.
CT findings of hemangioblastoma.
- Hypodense cyst.
2. Iso to hyperdense solid nodule.
T1WI of hemangioblastoma.
- Isointense nodule +/- flow voids.
T2WI of hemangioblastoma.
- Hyperintense cyst and nodule, possible surrounding hyperintense edema.
T1WI +C of hemangioblastoma.
- Avidly enhancing nodule, nonenhancing cyst, usually without cyst wall enhancement.
DWI of hemangioblastoma.
- Possible DWI-bright, ADC-dark diffusion restriction in cystic component.
MRS of hemangioblastoma.
- Elevated choline.
- Decreased NAA.
- +/- lactate/lipid peaks.
Basic description of intracranial lipomas.
- Fat containing developmental or congenital abnormalities of neural crest origin.
- Rarely neoplastic.
Pathology of intracranial lipomas.
- Arise secondary to abnormal differentiation of the meninx primitiva.
- Associated with other neural crest congenital anomalies in 60% of cases, often agenesis of the corpus callosum or underdevelopment of the inferior colliculus.
- Location: pericallosal region or within the quadrigeminal, suprasellar, or CPA cisterns.
General imaging characteristics of intracranial lipomas.
- Well marginated, low attentuation or high signal intensity mass (fat density).
CT findings of intracranial lipomas.
- Hypodense +/- peripheral calcification.
T1WI findings of intracranial lipomas.
- Hyperintense.
T1WI+C findings of intracranial lipomas.
- No enhancement.
Basic description of medulloblastoma.
- Malignant, invasive primitive neuroectodermal tumor usually arising within the posterior fossa.
- Most common pediatric malignant posterior fossa tumor.
Pathology of medulloblastomas.
- Divided into 4 molecular subtypes which originate in different locations:
- Wingless (WNT): cerebellar peduncles, CPA
- Sonic hedgehog (SHH): cerebellar hemispheres
- Group 3: 4th ventricle, midline
- Group 4: 4th ventricle, midline
General imaging features of medulloblastomas.
- Solid, rounded 4th ventricular mass most common.
- +/- 4th ventricular effacement and distortion (in comparison with ependymoma, which often expands/enlarges the 4th ventricle).
- Calcification and cysts occasionally present.
- Hemorrhage uncommon.
- CSF dissemination common, including drop mets within the spinal canal (15-50%).
Basic description of ADEM (acute disseminated encephalomyelitis).
- Autoimmune mediated demyelination typically occurring shortly after immunization or upper respiratory tract infection.