CNS Flashcards
What syndromes are associated with
Pilocytic Astrocytomas
NF-1
Possibly Li-Fraumeni, Noonan & TS?
What syndromes are associated with choroid papillomas?
Aicardi
Li-Fraumeni
&
Hypomelanosis of Ito
(tX;17(q12;p13))
What syndromes are associated with ependymomas?
NF2
What syndromes are associated with Medulloblastoma?
Gorlin
Turcot Type 2
&
Li-Fraumeni
What tumor belongs to this pathway?

Pilocytic astrocytoma
A duplication of results in KIAA1549-BRAF fusion protein with KIAA1549 replacing the BRAF N-terminal regulatory domain is associated with what tumor and how often?
Pilocytic astrocytoma:
70%
What is unique about pilocytic astrocytoma with loss of wild type NF1?
Grow in association with optic nerve
BRAF V600E mutation is associated with what CNS tumors?
Supratentorial pilocytic astrocytomas, gangliogliomas, PXA & DNET
What are the WHO grades for ganglioglioma and anaplastic ganglioglioma
WHO I
&
WHO III
(There is no WHO II)
What syndrome is associated with cerebellar ganglioglioma?
Cowden syndrome.
Bonus: gangliogloma in this location warrants genetic testing for Cowden syndrome.
What is the most common pediatric CNS malignancy?
2nd most common?
- Pilocytic astrocytoma
- Medulloblastoma
Assuming appropriate histology and stains, what required feature is necessary to make a diagnosis of medulloblastoma?
Primary tumor present in the cerebellum.
What is the immunoprofile of medulloblastoma?
What is in the differential?
Synaptophysin, GFAP, INI-1 retained.
Other embryonal tumors (medulloepithelioma, pineoblastoma, CNS neuroblastoma, embryonal mutated or NOS) and high grade gliomas.
What are the 4 (or 5) different diagnostic categories of medulloblastoma?
Other molecular associations, syndrome, histologic type and risk?
- WNT activated - beta catenin/CNNTB1; Turcot (T2); DN/classic; low risk/100% survival.
2a. SHH activated w/p53 WT - PTCH/LOH 9q22; Gorlin; DN/MBEN; intermediate; *bimodal age
2b. SHH activated w/p53 mutated - Li Fraumeni; LCA; high risk - Group 3 - MYC amplified, p53 & i17q; LCA; high risk, worst Px; CD133+
- Group 4 - i17q, MYCN; classic; intermediate risk
What is the most common subtype of medulloblastoma?
2nd, 3rd, 4th?
- Group 4 - 40%
- SHH p53WT - 26-27%
- Group 3 - 20%
- WNT activated - 10%
- SHH p53 mutated - 3-4%
What ages do the various medulloblastoma subtypes present?
- WNT - child to young adult
- SHH p53WT - bimodal: <4, teens/young adults
- SHH p53 mutated: 14-17 years old
- Group 3: infants
- Group 4: all ages
Large cerebellar mass in a 5 yo female.

Medulloblastoma, classic histology
(Probably WNT activated or Group 4)
Large cerebellar mass in a 2 year old male.
What is it? What is likely mutation? What syndrome to screen for? What is Px?

Medulloblastoma
SHH p53WT (PTCH1, SUFU)
Gorlin syndrome
Excellent px/low risk
What is the definitive treatment for medulloblastoma?
Complete surgical resection.
What is the ddx for medulloblastoma based on location?
Based on histology?
Location: Cerebellar astrocytoma, ependymom, hemangioblastoma, CNS Embryonal tumors
Histology: CNS Embryonal tumors, ATRT
C5-C6 nerve root damage
Erb palsy
Klumpke paralysis
Paralysis of wrists and digits due to trauma a C9-T1 nerve roots
What is this?

Area cerebrovasculosa: histologic appearance of anencephalic brain w/primitive superficial neural layer and subadjacent vascular layer.
Describe the types of Chiari malformations
Type 0: syringohydrocele without herniation
Type I: >5mm tonsilar herniation +/-syringocele; syndromic ass’n - Marfan, EDS
Type 1.5: >5mm herniation w/persistent syringomyelia
Type II: Arnold Chiari - <5mm tonsilar herniation w/low lying torcular herophili, tectal beaking, hydrocephalus w/clival hypoplasia & lumbosarcal meningomyelocele.
Type III: variable herniated elements w/occipital encephalocele
Type IV: ~cerebellar agenesis/hypoplasia
What is the Meckel Gruber Syndrome triad?
BQ: what is the mode of inheritance and what 3 genes are implicated?
- Occipital encephalocele (& other CNS malform)
- Cystic dysplasia b/L kidneys
- Duct-plate malformation liver
Mode: AR
Genes: MSK1 (Chr 17), MSK2 (Chr 11) & MSK3 (Chr 8)
What is this?

Alexander Disease - GFAP mution –>failure to myelinate –> wide spread white matter destruction
*Note the perivascular Rosenthal fibers
What is this?

Krabbe disease (aka Globoid Cell Leukodystrophy)
An AR lysosomal storage disease caused by galactosylceramidase deficiency
Presents in infancy
Fatal
What is this?

Metachromatic Leukodystrophy:
Arylsulfatase A deficiency –>accumulation of myelin toxic sulfatides stain pink on H&E & brown w/acid cresyl violet
Presents as peripheral neuropathy, psychomotor retardation & blindness beginning 1-2yo
*Asx inclusions can be seen throughout other tissues
What is this?

X-linked Adrenoleukodystrophy:
Xq28 peroxisomal storage disease affecting ALD transporter –> inability to process/accumulation of VLCFA –> demyelination & adrenal atrophy
*Note perivascular lymphocytes and aggregates of foamy histiocytes, & trilaminar lipids on EM
What defect in Smith-Lemli-Opitz syndrome results in holoprosencephaly?
Defective cholesterol synthesis - required for SHH cleavage (cholesterol binds corboxy-terminus allowing for autocleavage)
What is ass’d w/batwing ventricles or moose-head ventricles?
Agenesis/dysgenesis of corpus callosum leads to superior displacement of lateral ventricles and “batwing” shape.
Joubert Syndrome
Describe 3 types of holoprosencephaly
- Lobar
- Semilobar
- Alobar
Describe features of alobar holoprosencephaly

MC form in neuropath/autopsy service
Absent longitudinal fissure, horseshoe shaped holosphere, absent sylvian fissue, gyrus rectus and olfactory structures.
Can see dorsal cyst at membranous attachment at tentorium
What risk factors are associated with agenesis of the corpus callosum?
- Aicardi syndrome: retinal abns & seizures
- Ciliopathies: primary ciliary dyskinesia, Bardet–Biedl syndrome, Alström, Meckel–Gruber
- nonketotic hyperglycemia (inborn errors)
What is lissencephaly? What are the types?
Abnormality of cerebral surface
Type I - failed migration; agyric w/thickened neocortical grey matter & thin white
Type II - overmigration; focal agyric pattern with thickened grey matter
What genes and syndromes are ass’d w/Lissencephaly Type I?
LIS1 (17p13.3) - Miller-Dieker syndrome - facies, respiratory
XLIS (Xq22) - males = lissenceph; females = subcortical heterotopia
RELN (7q22) - cerebellar malformations
ARX (Xp21) - ambiguous genitalia
What syndromes are associated w/ lissencephaly Type II?
What is the cause?
- Fukuyama congenital muscular dystrophy - MC
- Walker-Warburg
- Muscle-eye-brain disease
- Congenital muscular dystrophy (MDC) 1D
- MDC-1C
*Defective glycosylation (O-mannosylation) - necessary in post-translational protein modification
What are the risk factors for polymicrogyria?
TORCH infections, metabolic disease (e.g. Zellweger), intrauterine ischemia, family hx, & FGFR3 mutation (thanotophoric dwarphism)
Describe the types of focal cortical dysplasia
Type I: Distortion of tangential layers w/heterotopic neurons in white matter.
Ia: w/o giant neurons
Ib: w/ giant neurons
Type II: w/dysmorphic neurons
IIa: +Type Ia; TSC2 gene
IIb: +Type 1a +balloon cells; TSC1 gene - indistinguishable from tubers
Type III: FCD w/ass’d lesion (low grade glioma)
When does microcystic encephalopathy occur? What is the associated infection?
Late in gestation: brain formation normal but with multiple foci of necrosis & cystic change
Ass’d w/HSV
What stains distinguish various cysts/cell types of CNS?
Neurenteric/dermoid: respiratory/GI w/BM substance - CK & EMA+, usually CK20 neg. Col-IV for BM
Rathke: same w/xanthogranulomatous inflam
Colloid: PAS+ contents, CK & EMA lining
Ependymal: GFAP & S100
Choroid: CK & S100
Pineal: 3 layers - GFAP (inner); pineal - synaptophysin (middle); CT (outer)
Blake pouch - meninges, ependyma & choroid
Arachnoid - EMA
What are the 4 categories of lysosommal storage disorders?
- Neuronal lipidoses-lipofuscin, cherry red ; accumulates in cytoplasm; Niemann Pick
- Leukodystrophies-demyelinating peripheral neuropathy; MLD, Krabbe, ALD
- Storage histiocytoses-Gaucher, Pompe, Niemann-Pick
- Mucopolysaccharidoses- accumulation in extracellular matrix too; CVD, cloudy corneas, skeletal abns, organomegaly -Hurler
What is Zellweger spectrum and what 3 disorders are categorized as Zellweger spectrum?
Peroxisomal biogenesis disorders involving PEX genes, w/VLCFA accumulation identifiable in plasma
- Zellweger syndrome - aka cerebrohepatorenal syndrome
- Neonatal ALD
- Infantile Refsum disease - less severe than Zellweger
What are the 6 leukodystrophies?
- Metachromatic: metachromatic material in CNS, PNS and viscera; herringbone, prismatic & tuft stone inclusions
- X-linked adrenoleukodystrophy: trilaminar inclusions; perivascular lymphocytes; foamy histiocytes
- Krabbe: perivascular globoid cells; hypertrophic “onion bulb” neuropathy; tubular inclusions
- Alexander disease: grossly cavitated; intermediate filaments
- Canavan disease (oligodendroglial & axonal sparing): NO macrophages/gliosis; vacuolation at gray-white junction; ladder-like cristae; aspartate accumulation
- Pelizaeus-Merzbacher disease: X-linked; perivascular, tigroid dysmyelination
What are 6 neuronal lipidoses?
- GM1 gangliosidosis: B-galactosidase (MPS)
- GM2 gangliosidosis: Tay-Sachs & Sandhoff (SH); hexosaminidase A &/or B
- Niemann-Pick A/B: Sphingomyelinase (SH)
- Niemann-Pick C: Cholesterol transport; axonal swell & neurofibrillary tangles; no cherry-red spot
- Farber Granulomatosis: ceramidase; hoarsness, arthropathy, SQ nodules
- Neuronal ceroid lipofuscinosis: osmiophilic deposits & fingerprint bodies; no cherry-red spot
*MPS: mucopolysaccharidosis; SH:storage histiocytosis
What are the sphingolipidoses?
- GM1 gangliosidosis: B-galactosidase
- GM2 gangliosidosis: Tay-Sachs, Sandhoff; hexosaminidase
- Niemann-Pick A/B: sphingomyelinase
- Gaucher: glucocerebrosidase
- Fabry: alpha-galactosidase; PN, CVD, bathing trunk telangiectasias, renal & eye dz
- Farber granulomatosis: ceramidase; lipid granulomas
What is this?
What is MELAS?

Ragged Red Fiber
M-Mitochondrial
E-Encephalopathy with
L-Lactic acidosis
A-And
S-Strokes
*Paracrystaline “Parking lot” inclusions
What is Pompe disease and what are its features?
Glycogen storage disease (glycogenosis type2) from alpha-glucosidase deficiency
Vaculor myopathy, cardiomegaly & macroglossia
Accumulation of membrane bound and free glycogen
Name and describe the 4 most common mitochondrial diseases
- MELAS - brain infarcts w/o vascular pattern in occipital lobes, cerebellum & deep gray; young-variable onset
- Myoclonic epilepsy w/raged red fibers (MERRF) - neuronal loss & gliosis in dentorubroolivary region, substania nigra & dorsal column; young
- Leigh: subacute necrotizing encephalopathy; symmetrical vasculonecrotic lesions in substantia nigra, brain stem & inferior colliculi - histology=Wernicke w/o hemorrhage; <2yo; AR inheritance
- Kerns-Sayre: eye findings, fatal cardiomyopathy /conduction, GI, renal & endocrine manifestations; chronic progressive external opthalmoplegia; deletion of mtDNA
What is the proposed cause of mitochondrial disorders?
How do these disorders cause dz?
What are the signs and sx of mitochondrial dz?
- Defects in assembly/formation of e-transport chain or in maintenance of mitochondrial DNA (mtDNA)
- Dysfunction of e-transport causes energy deprivation, free radical formation & apoptosis
- Encephalomyopathies; increased blood/CSF lactate and lactate to pyruvate ratio.
What are the microscopic features of mitochondrial dz/ragged red fiber muscle dz?
Ischemic-like changes, intramyelin edema, sestem degenerations & vascular mineralization in deep gray, adjacent white matter, dentate nucleus & brain stem.
Modified Gomori trichrome or SDH highlights proliferation of abnormal mitochondria in muscle (RRF)
EM: mitochondrial in concentric spirals, rectangular parcrystalline arrays (“parking lot” inclusions)
What dz categories are included in the amino acid disorders?
- Urea cycle
- Phenylketonuria
- Maple syrup urine dz
- Organic acidemias (propionic, methylmalonic)
Most sporadic/AR
What is the most common type of Congenital Disorders of Glycosylation?
CDG1a - psychomotor impairment, ataxia & alternating strabissmus; early stages often fatal, but can be survived.
- Olivaropontocerebellar atrophy
- Dysmorphic features: inverted nipples, subcutaneous buttock fat pads, contractures, MSK
EM: myelin-like lysosomal inclusions
What dz is characterized by POLG mtDNA depletion/mutation with CJD-like histology (spongiformencephalopathy) and shows neutral fat deposition in diseased brain tissue w/Oil Red-O?

Alpers-Huttenlocher Syndrome
What are the more common neurodegenerative disorders?
AR?
AD?
AR:
- Friedreich Ataxia
- Frataxin gene on 9q13 - iron transport
- Pes cavus, scoliosis, DM, cardiomyop
- Histology: DRG: neuronal depletion w/nodules of Nageotte; loss of sensory fibers in PNS - Ataxia Telangiectasia
AD:
- Spinocerebellar atrophies:
- Often trinucleotide repeats, or pentanucleotide repeats - dentatorubropallidoluysian atrophy, episodic ataxia 1 & 2
What is the gene responsible for Friedreich Ataxia?
What is affected?
- Frataxin gene on 9q13
- iron transport
What is the most common pathologic feature of autism?
Megaencephaly
Microscopically: neuronalmegaly in young, atrophy and drop-out in older patients
What is mesial temporal sclerosis?
Histology?
Stains?
Associations?
- Idiopathic - ass’d w/refractory seizures
- Identical to hypoxic ischemic injury - changes in CA1 & CA4 (endofolium) of hippocampus
- NeuN1 highlights neuronal loss and dispersion
- Ass’d w/prolonged febrile seizures in infancy