From: Subject: Differential Diagnosis in Neuroradiology Date: Tue, 13 Dec 2005 15:02:16 -0500 MIME-Version: 1.0 Content-Type: multipart/related; type="text/html"; boundary="----=_NextPart_000_0000_01C5FFF6.352E4670" X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0000_01C5FFF6.352E4670 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Content-Location: file://E:\ADDITIONS\NeuroDDX\Differential Diagnosis in Neuroradiology.htm Differential Diagnosis in Neuroradiology

Neuroradiology Differential=20 Diagnoses

(Original Text from = Spencer Gay,=20 MD, UVA)

HTML = Coding/Editing=20 by:
James G.=20 Smirniotopoulos, M.D.
Uniformed Services University of the Health=20 Sciences
Bethesda,=20 Maryland=20

Peer-Review by: Franz J. = Wippold II,=20 M.D.
Uniformed = Services=20 University of the Health Sciences
Bethesda, Maryland
and
Mallinckrodt Institute of Radiology =
Washington University of St. Louis =
St. Louis, = Missouri

Visit MedPix - The Online Medical Imaging Database

Vist the ACR Learning File on the Web

Please Read=20 Disclaimer

Return to Previous=20 Document

POSTERIOR FOSSA MASS -=20 CHILD
Cerebellum/IVth=20 Ventricle
- = Medulloblastoma -=20 midline, vermian or roof - usually hyperdense on plain CT - often = enhance=20 homogeneously - Astrocytoma
-=20 usually PILOCYTIC ASTROCYTOMA - 2/3 are cystic with mural nodule - cyst = fluid=20 denser than CSF due to protein
-=20 Ependymoma - INTRA-ventricular - "cast" of lumen - 50% are = calcified=20

Brainstem - Brainstem glioma - = expands=20 brainstem (infiltration w/o destruction) - hydrocephalus (may be=20 late)
Extraaxial fluid=20 collection
- Large = cisterna magna=20 ("Mega Cisterna Magna")
- = Epidermoid inclusion cyst
-=20 Arachnoid cyst (may bevel inner table of skull) - Dandy Walker cyst of = 4th=20 ventricle (look for vermian abnormalities)
- Vermian agenesis
- Chronic subdural hematoma =
COMMENT: For a posterior fossa mass one should = consider the=20 direction of displacement of the 4th ventricle to assess from which = compartment=20 it arises

POSTERIOR FOSSA MASS - = ADULT=20
Extraaxial:
- Vestibular Schwannoma (CPA) =
- Meningioma
-=20 Ependymoma

Intraaxial:
Metastasis - most common intraaxial neoplastic = post fossa=20 mass in adult
Hemangioblastoma -=20 cystic or solid - angio shows hypervascularity & stain=20
Astrocytoma - usually not vascular = on=20 angio
Medulloblastoma - = often more=20 lateral in adults Lymphoma Abscess Infarct

CEREBELLAR ATROPHY =
Drugs
-=20 Alcohol (vermis)
- = Dilantin=20 (hemispheres)
- = Chemotherapeutic=20 agents
Vascular process = (incl.=20 infarction)
Trauma=20
Hyperthyroidism =
Paraneoplastic - lung, breast, lymphoma, = ovary=20
Olivopontocerebellar = degeneration=20

COMMENT: Cerebellar sulci > 1 mm, = enlarged=20 4th ventricle, enlarged cisterns

MASS IN CLIVUS =
Chordoma - bone destruction =
Meningioma - hyperostosis
Local invasion
- nasopharyngeal cancer
- pituitary tumor
Metastasis
Chondrosarcoma (more often paramedian) =

COMMENT: A basilar artery aneurysm = may appear=20 to arise from the clivus - look for pulsationartifact in the phase = encoding=20 direction

BRAINSTEM LESION =
Brainstem glioma
- present with cranial nerve palsies=20
- hydrocephalus less = common=20
Infarction
Hemorrhage - often hypertensive =
Pontine myelinolysis ("central", aka. "Osmotic=20 Myelinolysis")
Multiple=20 sclerosis
Metastasis=20
Basilar artery = aneursym/dolichoectasia may=20 displace brainstem

CEREBELLOPONTINE ANGLE = TUMOR=20
Vestibular Schwannoma (aka. = "Acoustic=20 neuroma")
- enlarges IAC, = rounded=20 mass in cistern
- = enhances with IV=20 contrast and Gadolinium DTPA
-=20 large (>2.5 cm) schwannomas heterogeneous
- bilateral lesions in NF-2 =
Meningioma
-=20 does not enlarge IAC
- = enhances=20 homogeneously
Epidermoid=20
- hypodense
- enlarges cistern
- serpentine margin
- FLAIR sequence may distinguish from CSF = (arachnoid=20 cyst)
Exophytic brainstem = glioma
- progressive = cranial nerve=20 palsies
Acquired = Epidermoid=20 ("Cholesteatoma")
-erupts = from=20 middle ear
- signs of = mastoiditis,=20 Hx of ear infection
Metastasis
Basilar artery aneurysm
Glomus jugulare
Trigeminal schwannoma (may "dumbell" into middle=20 fossa)
Arachnoid cyst = (homogeneous=20 CSF density and signal)

CT PROGRESSION OF INTRACRANIAL=20 HEMATOMA
(change from = HYPER- to=20 HYPO- dense over time)
Initially -=20 60 - 90 Hounsfield Units (HU)
2=20 days - 70 HU
3 weeks - 30 = HU
>5 weeks - <30=20 HU
20% show enhancing rim = at 2-6=20 weeks

MRI APPEARANCE OF INTRAPARENCHYMAL=20 HEMATOMA
(T1/T2: II, ID, = BD, BB, DD=20 (I-iso, D-dark, B-bright)
Hyperacute - minutes to hours (DD =3D> = II)=20
- T1WI - hematoma hypointense = (deoxyHb) =3D>=20 isointense
- T2WI - = hematoma=20 hypointense (deoxyHb) =3D> isointense
Acute - 0-2 days (ID =3D> BD) =
- deoxyhemoglobin in intact RBCs with surrounding = edema
- T1WI - hematoma = isointense,=20 low signal intensity (SI) edema
-=20 T2WI - hematoma decreased SI at center, high SI edema =
Subacute - 2-14 days (BB)
- deoxyhemoglobin changes to methemoglobin from = outer to=20 inner
- T1WI - outer core = shows=20 increased SI
- T2WI - = Outer core=20 shows increased SI due to shortened T1, longer T2 =
Chronic - 14 days (BB =3D> DD) =
- hemosiderin laden macrophages at = periphery=20
- T1WI - inner core now also = increased SI, rim=20 has low SI
- T2WI - inner = core also=20 has increased SI, rim has low SI
Chronic - months later (DD) =
- hemosiderin laden macrophages at = periphery=20
- T1WI - mostly iso-/decreased SI, = rim has=20 lower SI
- T2WI - = markedly=20 hypointense rim has low SI - "blooms" with greater = T2-weighting=20
COMMENT: T1WI =3D T 1 weighted image = T2WI =3D T 2=20 weighted image SI =3D signal intensity

CT PROGRESSION OF ISCHEMIC = INFARCT=20
Initially - 30 HU =
1 day - <30 HU
Enhance ~3 days till 6 weeks =
Mass effect peaks at 3-5 days =
- seen in 20 % of ischemic infarcts =
- a significant mass effect is a poor prognostic=20 sign
After 8th week - 50% = have=20 "negative mass effect" (atrophy)

CAUSES OF SUBARACHNOID = HEMORRHAGE=20
Trauma (most common, but different = clinical=20 presentation)
* Ruptured = aneurysm=20 (classic "Worst HA of my life!")
*=20 Arteriovenous malformation
Neoplasm
Hypertensive hemorrhage (after rupture through = brain or=20 ventricle)

COMMENT: CT identifies a subarachnoid = hemorrhage in upto 80 - 95% of cases.
A negative CT does not rule out a small = subarachnoid=20 hemorrhage - therefore LP needed with classiscHx. =
SAH =3D> angiogram. If 1st angio negative = (spasm, clot,=20 etc) then follow-up angio in 2-4 wks.
After 2 normal angio =3D> workup spine for = source of blood=20 (e.g. spinal AVM, spinal neoplasm (ependymoma)).

SUBDURAL vs. EPIDURAL =
Subdural
-=20 Crescentic shape
- Can = layer along=20 falx or tentorium
- Acute = 1-7=20 d
- dense on = CT=20
- MRI isointense on T1WI, decreased = on=20 T2W
- Subacute 7-21 = d=20
- isodense on CT =
- MRI increased on T1WI and T2WI =
- Chronic >21 d
- hypodense on CT, may have enhancing = rim=20
- MRI decreased intensity on T1WI, = isointense=20 on T2WI

Epidural
- Biconcave (lenticular)
- Does not cross cranial sutures (unless Fx = crosses or=20 previous surgery)
- = OUTSIDE=20 (external) to dural sinus
- middle=20 fossa common (laceration of middle meningeal artery) =
- may occur in posterior fossa after Fx lacerates = transverse sinus

INTRAVENTRICULAR TUMOR =
Colloid cyst
-=20 often at foramen of Munro (3rd ventricle)
- hyperdense and enhancing =
Choroid plexus papilloma
- usually in lateral ventricles in = infants=20
- more often in 4th ventricle in=20 adults
Meningioma=20
- uncommonly
Ependymoma
-=20 4th ventricle
Metastasis = - to=20 choroid plexus
Subependymal Giant=20 Cell Astrocytoma (f. of Monro, attach to caudate, 90% have Tuberous=20 Sclerosis)
Astrocytoma=20
Central Neurocytoma (usually = attached to=20 septum pellucidum)

COMMENT: Both CPP and Meningioma = arise within=20 choroid, and derive blood supply from choroid vessels.

3rd VENTRICULAR MASS =
Anterior
-=20 Colloid cyst
-=20 Meningioma
- = Ependymoma=20
- Choroid plexus papilloma (least = common=20 location)
- AVM=20 (unusual)
- Basilar = artery aneurysm=20 (exotic)
Posterior=20
- Pineal region tumors (see = below)=20
- Tectal glioma =
- Epidermoid
-=20 Meningioma

COMMENT: The 3rd ventricle is least = common=20 location for ependymoma and CPP.

PINEAL REGION TUMOR =
Germ cell origin (about 60%) =
- Germinoma
-=20 40 - 50% of ALL pineal region tumors
- 2/3 of all Germ-cell origin tumors=20
- tumor surrounds calcified = gland=20
- homogeneous, dense on plain = CT=20
- Teratoma
- heterogeneous
- may have fat/lipid
- Teratocarcinoma
- Embryonal cell/yolk = sac/choriocarcinoma

Pineal parenchymal tumors=20
- exploded calcification=20
- radiosensitive =
- Pineocytoma
- hyperdense
-=20 Pineoblastoma - very malignant, a type of PNET
Tectal glioma
Meningioma (falx, tentorium) =
Metastasis
Vein of Galen Malformation (including aneurysmal = dilatation=20 of vein of Galen)

EXTRA-AXIAL TUMORS =
Meningioma
-=20 parasagittal > convexities > sphenoid ridge > subfrontal >=20 juxtasellar > tentorial > posterior fossa > floor of middle = cranial=20 fossa
Epidermoid=20
- Dermoid
- Lipoma (midline, ALL fat, may have callosal=20 agenesis)
Arachnoid = cyst=20
Bony lesion
Meningeal infiltration by lymphoma or leukemia = (may look=20 epidural/subdural in shape) Carcinomatous meningitis

SUPRATENTORIAL TUMOR =
Glioma (30-40%)
- Glioblastoma (astro grade IV) =
- Astrocytoma
- Oligodendroglioma
- Ependymoma
Metastasis (20-30%)
Meningioma (16%)
Pineal gland tumors
Lymphoma

BASAL GANGLIA = CALCIFICATIONS=20
Birth anoxia
Idiopathic (most common) bilateral and=20 symmetrical
Radiation = TX=20
Toxoplasmosis / CMV - usually not = limited to=20 basal ganglia
Hypoparathyroidism /=20 pseudohypoparathyroidism
Infarct

COMMENT: * BIRTH *

SUPRASELLAR MASS =
("SATCHMOE" - nickname for Louis Armstrong, = deceased jazz=20 musician extraordinaire)
Sellar/Parasellar neoplasm =
- pituitary adenoma
Aneurysm - sharply marginated - densely enhancing = on CT,=20 "pulsation artifact" on MR
Germ=20 Cell tumor ("ectopic pinealoma" - a misnomer)
Teratoma - heterogeneosu,iso-/lipid - small -=20 solid
Craniopharyngioma - = children>adults - calcified 75% - cystic 75%
Hypothalamic glioma - children / =
Histiocytosis (Diabetes Insipidus) =
Meningioma / metastasis
Optic glioma - erodes sphenoid - visual = loss=20
Epidermoid/Dermoid inclusion = cyst=20

COMMENT: For parasellar mass, add=20 carotid-cavernous fistula and cavernous or other carotid = aneurysm=20

SELLAR MASS
Pituitary adenoma
Craniopharyngioma
Meningioma
Metastasis
Epidermoid
Abscess
Aneurysm
Pituitary bleed - apoplexy (post-partum or into=20 adenoma)
Pituitary=20 sarcoid
Rathke cleft cyst = (usually=20 intrasellar, may extend out)
Germinoma

RING ENHANCING LESION (CT) =
Primary brain tumor = (glioblastoma) -=20 irregular thick ring
Metastasis=20 (especially if on ChemTx)
Abscess
- ring=20 is more smooth and regula
r -=20 thinner on medial (WM) side
Multiple sclerosis - in white matter=20
Resolving hematoma - 10-21 days - = usually has=20 perilesional lucency
Tuberculoma -=20 associated extracranial TB often found - irregular ring =
Infarct
Radiation necrosis - 9 months-3 years after Rtx = > 4000=20 rads
Postoperative change = (at edges=20 of resection)
Aneurysm - = due to=20 intraluminal thrombus

LOW DENSITY MASS LESION = (CT)=20
Lipoma - (-) CT # (- 60 -90 HU, not = merely=20 low, but very low)
Epidermoid - due=20 to inclusion of ectoderm
- often=20 lateral, occasional midline
Arachnoid cyst - CSF density/intensity =
- most at temporal tip/ middle fossa = P
orencephalic cyst = (brain=20 defect)
Infarct (acute = from edema,=20 chronic from encephalomalacia)
Pilocytic astrocytoma (cyst fluid) =
Ventricle/cistern
Chronic subdural

HYPERDENSE LESION WITHOUT = CONTRAST=20
Meningioma
- 20% also show hyperostosis =
- 2/3 show peritumoral edema =
Lymphoma (small round blue-cell tumor - densely=20 cellular)
- primary is = usually=20 intraaxial
- secondary is = often=20 extraaxial
Metastasis - * = MRCT *=20 Melanoma/Renal cell Ca/Choriocarcinoma/Thyroid
Medulloblastoma (small round blue-cell tumor - = densely=20 cellular)
Glioblastoma=20
Ependymoma
Colloid cyst (inspissated mucus) =
Hemorrhage (acute) / hemorrhagic = infarct=20
Craniopharyngioma =
Germinoma (pineal and suprasellar) =

MULTIPLE ENHANCING LESIONS =
Hematogenous: =
Metastases
-=20 45 -55% of CNS mets multiple
-=20 >2cm often cavitate
- = usually=20 near gray-white junction (peripheral > central) =
Lymphoma
-=20 usually deeper, periventricular, may be rings in
AIDS Disseminated infection (multiple = abscesses)=20
Multifocal infarction =

Inflammatory/Unknown = Etiology:=20
Multiple Sclerosis (white matter=20 lesions)
Vasculitis=20
Hypertensive = Crisis/Ecclampsia

Inherited Mass = Lesions/Neoplasms:=20
Hemangioblastoma (von=20 Hippel-Lindau)
Arteriovenous=20 malformations (cavernous hemangioma >> AVM) Meningiomas - 4% are = multiple=20 (some with NF-2, most without)
Multicentric gliomas - 5% of all = gliomas=20
Tuberous sclerosis =
Neurofibromatosis (both types - NF1 = (von=20 Recklinhausen) and NF2 (MISME)

GYRAL ENHANCEMENT: =
* Ischemia/Infarction (incl. seizures, migraines, = etc.)
* = Cerebritis/Encephalitis=20 (e.g. Herpes)
Meningeal=20 carcinomatosis (carcinomatous meningitis)
Meningitis - chronic > acute =
AVM
Cortical=20 vein thrombosis
Lymphoma=20
Meningioangiomatosis = (NF2)

COMMENT: Sturge-Weber will be dense = without=20 contrast due to tram track calcification in cortex underlying a = meningeal venous=20 angioma

CAUSES OF HYDROCEPHALUS (literally = "water on=20 the HEAD")
Communicating = (decreased=20 reabsorption)
- Normal = pressure=20 hydrocephalus
- prominent = temporal=20 horns
- s/p infection -=20 meningitis
- s/p = subarachnoid=20 hemorrhage
- Dural vein=20 thrombosis

Non-communicating (mechanical = obstruction to=20 flow)
- Aqueductal=20 stenosis
- = postinflammatory or=20 congenital
- Tumors - = especially=20 colloid cyst
- Congenital = anomalies
- Dandy-Walker = cyst of=20 4th ventricle
- = Arnold-Chiari=20 malformation

Overproduction (increased=20 production)
- Choroid = plexus=20 papilloma
COMMENT: = Mimicked by=20 atrophy - "hydrocephalus ex vacuo"

MIDLINE SHIFT
Intracranial mass
- Tumor
-=20 Large infarct with edema
-=20 Intracerebral bleed

Extracerebral collection=20
- Epidural hematoma =
- Subdural hematoma
- Empyema

Unilateral atrophy

HYDROCEPHALUS vs. ATROPHY = (CT)=20
Hydrocephalus (ventricles >>=20 sulci)
- Ballooned and = tight=20 frontal horns - Dilated temporal horns
- Dilated 3rd (hourglass shape) with flow void on = MR
- decreased = mammillopontine=20 measurement (expanded 3rd pushes mammillary bodies post./inf. =
- Dilated 4th ventricle=20
- Periventricular abnormal=20 signal/density

Atrophy (sulci and ventricles dilate=20 proportionately)
- Large = cortical=20 sulci
- Less 3rd = ventricular=20 dilatation (with parallel sides NOT hourglass shape) =
- Increased with age

COMMENT: Normal pressure = hydrocephalus=20 evaluated by nuclear cisternogram. No migration of activity over=20 convexities/persistent intraventricular activity ... 50% aided by shunt = ("shunt=20 responsive NPH")

APPROACH TO INTERPRETATION OF=20 ANGIOGRAPHY
What view = (lateral,=20 frontal, oblique, submental-vertex, etc)?
What Vessel Was Injected?
What phase (arterial, capillary, venous) of=20 injection?

Localize lesion = (hypervascular/hypovascular,=20 mass effect?, shift?)
Check vessels=20 for displacement
- don't = forget=20 extracerebral lesions
AP = - Anterior=20 cerebral arteries, pericallosal
-=20 Internal cerebral veins
- = Sylvian=20 point
LAT - Sylvian=20 triangle
POSTERIOR = CIRCULATION=20 (verterbral injection)
- = Precentral=20 cerebellar vein
- = PICA=20

Characterize vascularity - increased = (Hyper) or=20 decreased (Hypo)

BRANCHES OF INTERNAL = CAROTID=20
Meningohypophyseal trunk (that = "Italian=20 artery" Bernasconi-Casanari)
Ophthalmic
Superior hypophyseal
Posterior communicating (infundibulum, connects = to=20 PCA)
Anterior = choroidal =20 (AChoA - marker for temporal lobe herniation)
Anterior cerebral (ACA)
- Frontopolar
- Callosomarginal
- Pericallosal
Middle cerebral (MCA)
- Lenticulostriate (perforators to basal=20 ganglia)
Internal Carotid = (ICA)
-=20 Cervical-Petrous-Cavernous-Supraclinoidsegments

POSTERIOR CIRCULATION = BRANCHES=20
Vertebral
- Muscular (occipital) branches =
- Meningeal branch
- PICA Basilar
- AICA
-=20 Superior cerebellar (SCA)
-=20 Posterior cerebral (PCA)
-=20 Posterior communicating
- = Posterior=20 choroidal (medial/ and lateral branches)
- Parietoccipital
- Posterior temporal
- Calcarine

EXTERNAL CAROTID BRANCHES=20
Superior thyroid =
Lingual
Facial
Ascending pharyngeal
Occipital
Posterior auricular
Superficial temporal
Internal maxillary
- Middle meningeal (f. spinosum)

DEEP VENOUS DRAINAGE =
Anterior septal
Thalamostriate
Internal cerebral veins (paired) =
Basal vein(s) of Rosenthal (medial temporal=20 lobe)
Great vein of=20 Galen
Inferior sagittal = sinus (free=20 edge of Falx)
Straight=20 sinus
Superior sagittal = sinus=20 (don't forget the "Torcular Herophilus")
Transverse sinus
Sigmoid sinus
Internal jugular

COMMENT: Superficial drainage is = superficial=20 middle cerebral vein, vein of Trolard and vein of Labbe to superior = sagittal=20 sinus

CAUSES OF EARLY DRAINING VEIN - = (rapid or short=20 "transit time")
* = Neoplasms -=20 primary or secondary
* = AVM=20 Inflammatory lesion
Trauma=20 (hyperemia)
Ischemia=20
Epileptic focus =
Toxic encephalopathy

COMMENT: Definition is vein seen < = 3 sec=20 after beginning of intracerebral contrast - usually veins drain into Sup = Sinus=20 from anterior to posterior

CRANIAL FORAMINA AND = CONTENTS=20
Cribiform plate - CNN-I - Olfactory = nerve=20 twigs to nasal vault
Optic canal -=20 CNN-II - Optic nerve and ophthalmic artery
Superior orbital fissure
- III - Oculomotor, IV - Trochlear, V1 - = Ophthalmic , VI -=20 Abducens, superior ophthalmic vein
f. Rotundum - V2 Maxillary =
f. Ovale - V3 Mandibular and accessory meningeal=20 artery
f. Spinosum - = Middle=20 meningeal artery
f. = Internal=20 auditory canal - VII (Facial), VIII (Vestibulo-Cochlear) =
f. Jugular - Jugular vein, IX -- = Glossopharyngeal, X -=20 Vagus, XI- Accessory
f.=20 Hypoglossal - XII Hypoglossal
f.=20 Magnum - Spinal cord, XI Accessory, vertebral arteries, spinal=20 arteries

APPROACH TO INTERPRETATION OF=20 MYELOGRAPHY
Check plain = films - for=20 bone destruction, previous surgery, trauma, dysraphism =
Contrast used - water-soluble, oily =
Filling defects, displacement of sac, cord = ?=20
Compartment involved: =
CLASSIC:
Intramedullary (cord lesion) =
Extramedullary/Intradural (subarachnoid = space)=20
Extradural (outside the thecal = sac)=20
Conus (How low?) =
Roots (Thickend, clumped, displaced?)=20
Thecal sac (Narrowed? = Stenosis?)=20

INTRAMEDULLARY LESION =
Tumors
-=20 Ependymoma (most common, esp in adults)
- Astrocytoma (more common in children/Cx=20 location)
- = Medulloblastoma (CSF=20 seeding)
-=20 Lipoma/Dermoid/Epidermoid - especially in dysraphism =
- Hemangioblastoma (Von Hippel-Lindau = syndrome)=20
- Metastasis - = breast/lung/melanoma=20
- = Syringomyelia/Hydromyelia=20
- Hematoma Inflammation - = myelitis=20
- AVM-Angioma =
Cervical - usually glioma or syrinx =
Thoracic - consider teratoma, dermoid,=20 astrocytoma?

EXTRAMEDULLARY/INTRADURAL = LESION=20
Meningioma (most = thoracic)=20
Schwannoma (more common than=20 neurofibroma)
Neurofibroma (erodes=20 bone while extending through neural foramen, usually NF-1)=20
Drop metastasis -=20 medulloblastoma/ependymoma/pineal dysgerminoma/glioma =
Dermoid-Epidermoid (associated with dysraphism=20 ?)
Lipoma - most common = location is=20 caudal (also "fatty filum")

COMMENT: Most tumors in this location = are=20 benign

EXTRADURAL LESION =
Herniated disc (90% at L4-5 and L5-S1) =
Osteophyte
Metastasis (Breast-Lung)
Lymphoma
Meningioma
Primary Bone tumor:
- Chordoma
-=20 Osteosarcoma/blastoma
-=20 Myeloma
- Aneurysmal bone = cyst
- Giant cell = tumor=20

Neurofibroma (often w/intradural=20 component)
Dermoid-Epidermoid/Lipoma

SACRAL EXPANSILE LESION =
Sacrococcygeal Teratoma (often presents in=20 newborn)
Epidermoid = cyst=20
Chordoma (bulky, lobulated mass with = bone=20 destruction)
Dural = ectasia -=20 meningocele
Dermoid=20
Lipoma
Giant cell tumor
Aneurysmal bone cyst

OPTIC NERVE THICKENING =
Optic nerve glioma (usually pilocytic, often with = NF1)
Optic nerve sheath = meningioma=20 (tram track lesion outlines normal size nerve)
Papilledema (dilations of SAS that surrounds=20 nerve)
Optic neuritis=20 (MS-Sarcoid)
Orbital=20 pseudotumor
- near = globe=20
- responds to steroid = therapy=20
- thickens muscles AND = tendons=20
Graves' disease =
- thickens extraocular muscles =
- no tendon=20 involvement
Vascular=20 malformations
- cavernous = hemangioma > AVM
-=20 carotid-cavernous fistula
Orbital=20 cellulitis - may be 2nd to ethmoid sinusitis Leukemia Perineuritis Optic = nerve=20 hemorrhage

COMMENT: Check optic chiasm for = intracranial=20 extension

OCULAR MASS
Child
-=20 Retinoblastoma
- 2/3 = "heritable",=20 1/3 w/Family Hx
-=20 multiple/bilateral if "heritable"
-=20 90% Ca++
- staging = (vitreous,=20 choroidal, scleral, extension?)

Adult
- Choroidal melanoma
- older patient, enhance
- Metastasis - breast, lung, extra-ocular=20 melanoma
- Intraocular=20 lymphoma
- Choroidal=20 hemangioma

RETRO-OCULAR MASS = (Intraconal)=20
Hemangioma
- enhance - phleboliths seen in 10% =
Optic nerve glioma
Optic nerve meningioma
Angioma
Lymphangioma
AVM

CONAL MASS
Rhabdomyosarcoma
- bone destruction
- calcification
Thyrotoxic ophthalmopathy
- 88% bilateral
- 80 % medial, inferior rectus muscles =
Myositic pseudotumor

EXTRACONAL MASS =
Dermoid Mucocele
- occurrence frontal > ethmoid > maxillary = >=20 sphenoid
* = FEMS=20
* Lymphoma
Pseudotumor

LACRIMAL GLAND MASS =
Unilateral
-=20 Pleomorphic adenoma (histo similar to minor salivary gland = tumors)=20
- benign
- Malignant epithelial cell tumors =
- Adenoid cystic carcinoma =
- bone destruction

- Pseudotumor - = Dacroadenitis

Bilateral (systemic = diseases)=20
- Lymphoma
- Sarcoid
-=20 Collagen vascular disease

RADIOLUCENT SKULL LESION=20
Metastasis
Normal variant
Epidermoid (intradiploic)
Eosinophilic granuloma ("beveled" = margins)=20
Plasmacytoma
Paget's (widened diploic space) =
Burr hole
Fibrous dysplasia (widened diploic = space)=20
Hemangioma (widened diploic space, = radial or=20 starburst trabeculae)
Brown tumor=20 of hyperparathyroidism
Osteomyelitis
Erosion from intracranial tumor (usu = slow-growing, e.g.=20 meningioma, oligodendroglioma)

OPAQUE PARANASAL SINUS =
Acute sinusitis - FLUID
Fracture (blood)
Chronic sinusitis - MUCOSAL THICKENING =
Mucocele (obstructed sinus ostium = =3D>=20 expanded sinus)
Retention = cyst=20 (obstructed mucus gland =3D> round mass)
Polyp
Normal=20 hypoplastic

- OTHER
Cystic fibrosis
Inverting papilloma (bone destruction) =
Malignant tumor

EXPANSILE LESION OF SINUS=20
Fibrous dysplasia =
Mucocele
Ossifying fibroma
Extensive polyposis (allergic = history?)

PHAKOMATOSES
Tuberous sclerosis
- Autosomal dominant
- Adenoma sebaceum, seizures, mental = retardation=20
- Hamartomas involving many organs,=20 angiomyolipomas of kidneys
- Brain=20 - periventricular subependymal nodules
- Cortical tubers
- 15% develop subependymal giant cell=20 astrocytoma

Sturge-Weber (Encephalotrigeminal = angiomatosis=20 )
- No inheritance = pattern,=20 congenital malformation
- = Port wine=20 nevus of face
- V1=20 distribution
- Seizures, = mental=20 retardation, glaucoma
- = CT - gyral=20 calcification and cerebral atrophy
- MR - gyriform enhancement - mass-like choroid=20 plexus
- calvarial/facial = thickening
- hemiatrophy = and=20 hemiparesis

Von Hippel-Lindau =
- Hemangioblastomas - cerebellum, retina, = medulla, spinal=20 cord
- Pheochromocytoma = (NIH Type=20 2a or 2b)
- Renal cysts=20 60%
- Renal cell = carcinoma=20 45%
- Pancreatic cysts, = Islet cell=20 tumors, serous adenomas

Von Recklinghausen (Neurofibromatosis = Type 1,=20 NF1)
- Autosomal=20 dominant
- Cafe-au-lait = spots 6 or=20 more, 15mmm in adult
- = fibroma=20 molluscum (multiple cutaneous neurofibromas) - Sphenoid dysplasia - = Acute=20 kyphotic scoliosis
- = Lateral=20 thoracic meningocele
Type = I -=20 chromosome 17 - "peripheral" type (misnomer)
- Peripheral neurofibromas - Other CNS tumors - = glioma,=20 optic glioma

Wishart Neurofibromatosis (Bilateral = Vestibular=20 Schwannomas) Type II
- = chromosome=20 22 - "central" type (misnomer)
(aka=20 MISME Syndrome: Multiple Inherited Schwannomas, Meningiomas, and=20 Ependymomas)
- Bilateral = vestibular=20 schwannomas in "all" patients
-=20 Other CNS tumors - meningioma, spinal cord ependymoma, other cranial and = spinal=20 schwannomas

COMMENT: The gliomas of NF-2 = are=20 ependymoma, those in NF-1 are astrocytoma (both pilocytic and=20 glioblastoma)

One of the=20 most important clinical differential diagnoses of vCJD is sCJD. = MRI

differentiates = between the two=20 forms of the disease in most cases. The tha-

lamic=20 hyperintensity occurs in sCJD and familial CJD but no case has=20 been

reported showing the = pulvinar=20 to be brighter than the putamen. Other con-

ditions that cause = thalamic=20 hyperintensity include CO poisoning, Japanese

Nipositu = encephalitis,=20 Wernicke=92s encephalopathy, bithalamic glioma,=20 and

thalamic infarction = (basilar=20 artery or deep cerebral venous thrombosis), benign

intracranial = hypertension=20 (BIH), and post-infectious encephalitis ...

metabolic, toxic, = infectious,=20 vascular -- art or venous

END OF SECTION =

One of = the most=20 important clinical differential diagnoses of vCJD is sCJD. = MRI

differentiates=20 between the two forms of the disease in most cases. The = tha-

lamic=20 hyperintensity occurs in sCJD and familial CJD but no case has = been

reported showing=20 the pulvinar to be brighter than the putamen. Other con-

ditions that=20 cause thalamic hyperintensity include CO poisoning, = Japanese

Nipositu=20 encephalitis, Wernicke=92s encephalopathy, bithalamic glioma, and

thalamic=20 infarction (basilar artery or deep cerebral venous thrombosis),=20 benign

intracranial=20 hypertension (BIH), and post-infectious encephalitis