Graphic representation of approximate

relative

prevalence of primary vs. metastatic brain

tumors in

adults. In clinical series, nearly half of all

adult eNS

neoplasms are metastases.

Graphic shows relative prevalence of brain

tumors in

children. Metastases, M/GBMs are rare.

Low grade

astrocytomas, PNETs {including

medulloblastoma} are

more common compared to adults.

WHO Calcifications'

Neuroepithelial tumors

Nerve sheath tumors

Meningeal tumors

Metastases

Lymphoma

Cysts

Germ cell tumors

Neuroepithelial tumors [ Gliomas ]

40-45% of all intracranial tumors

BRAIN TUMERS

Classification • World Health Organization (WHO) divides

CNS neoplasms into primary (9 basic

groups) and secondary tumors(metastases

1-Neuroepithelial

tumors o Astrocytic neoplasms: Derived

from neoplastic astrocytes; vary in location,

peak age, genetics,clinical features and

biological behavior as well as

imaging appearance

• Diffusely infiltrating (most commonly

fibrillary) astrocytomas

• Subependymal giant cell astrocytoma

Oligodendroglioma: Putative origin from

oligodendrocytes, • Oligodendroglioma

• Anaplastic oligodendroglioma

• Mixed glioma (2 or more neoplastic

elements;

mixed oligo-astro most common)

Other gliomas of uncertain origin

o Other gliomas of uncertain origin • Astroblastoma

• Chordoid glioma of the 3rd ventricle

o Ependymal tumors: Tumors that

arise from ependymal lining of ventricles,

central canal of spinal cord

• Ependymoma

• Subependymoma

o Choroid plexus tumors • Choroid plexus papilloma

• Choroid plexus carcinoma

• Pleomorphic xanthoastrocytoma

2- Neuronal, mixed glial-neuronal and neurocytic tum (neoplasms with variable neuronal and/or glial differentiation)

o Ganglioglioma and gangliocytoma (in cerebellum Lhermitte-Duclos disease

o Desmoplastic infantile ganglioglioma/astrocytom

o Dysembryoplastic neuroepithelial tumor (DNET

o Hypothalamic hamartoma

o Central neurocytoma and parenchymal(extraventricular) neurocytic tumors

• Pineal parenchymal tumors: Derived from pineocyt

(pineal parenchymal cells) or embryonic prercursor with wide spectrum of differentiation

o Pineoblastoma o Pineocytoma

3-Embryonal tumors: Round-cell tumors with variable spectrum of

differentiation; some neuropathologists classify all these as primitive neuroectodermal

tumors(PNETs)

o Medulloepithelioma

o Ependymoblastoma

o Medulloblastoma (posterior fossa primitive neuroepithelial tumor or PNET-MB)

o Primitive neuroepithelial tumor (supratentorial small round cell embryonal tumor

o Atypical teratoid/rhabdoid tumor (AT/RT)

4- Peripheral neuroblastic tumors: Tumors with wide

range of neuronal differentiation, may involve/invade CNS

o Neuroblastoma (when involves CNS, is usually metastatic from extracranial site)

5- Tumors of cranial and spinal or peripheral nerves: Tumors with wide range of

histopathological features;

multiple tumors in skull/brain are associated with inherited familial tumor syndromes (Le.neurofibromatosis)

o Neurofibroma

o Schwannoma

o Malignant peripheral nerve sheath tumor (MPNST)

6- Meningeal tumors o Meningothelial cell tumors (e.g., meningioma)

o Mesenchymal, nonmeningothelial cell tumors (e.g.,chondrosarcoma)

o Tumors of uncertain histogenesis (e.g.,hemangioblastoma)

•

7- Lymphoma and tumors of hemopoietic system: May be primary or

secondary, variably involve skull,meninges, and/or brain

o Lymphoma o Plasmacytoma o Leukemia (granulocytic sarcoma)

8- Germ cell tumors: Broad histopathological spectrum of extragonadal germ cell neoplasms with

variable

biological behavior

o Germinoma o Teratoma o Embryonal carcinoma

o Others (e.g., yolk sac tumor, choriocarcinoma,

mixed germ cell tumors)

9-Metastatic tumors and remote effects of cancer on the CNS o Metastases (brain parenchyma, other sites such as

meninges and pituitary gland)

o Paraneoplastic syndromes

Tumors in children < 2 yrs

• Astrocytoma

• Choroid plexus papilloma

• Teratoma

• Embryonal tumors

Cortically-based tumors

• DNET

• Ganglioglioma

• Oligodendroglioma

• PXA

Intraventricular tumors

• Ependymoma, subependymoma

• Central neurocytoma

• Choroid plexus papilloma/carcinoma

Pineal region tumors

• Pineal parenchymal tumors

(pineocytoma/blastoma

• Germ cell tumors (germinoma,teratoma,etc)

• "Other" tumors/masses in

o Meningioma (tentorial apex)

o Astrocytoma (rare in pineal gland;

more common in tectum, thalamus)

o Nonneoplastic pineal cyst

Dural-based tumors and mimics

• Meningioma

• Metastasis

• Inflammatory pseudotumor

• Infection (e.g., tuberculosis)

• Extramedullary hematopoiesis

Local intracranial extension from

extracranial

neoplasms

• Chordoma

• Paraganglioma

• Carcinomas (e.g., nasopharyngeal

squamous cell),

sarcomas (rhabdomyosarcoma)

Neoplasms that often have cyst + nodule

• Pilocytic astrocytoma

• Craniopharyngioma

• Ganglioglioma

• Hemangioblastoma

Tuberous sclerosis

Tuberous sclerosis

Choroid plexus tumors

• Papilloma and carcinoma

o Vivid enhancement

o ± CSF seeding

o Parenchymal invasion and peritumoral edema with

choroid plexus carcinoma Astrocytoma

• Origin ~ septum pellucidum fornices or medial basal

ganglia

o Common pediatric intra-axial neoplasm

o Variable enhancement, Ca++ rare

Germinoma

• Hugs midline, often arises near third ventricle

• Early diabetes insipidus

• Early CSF spread

Subependymoma

• Inferior fourth and frontal horn most common

locations

• Nonenhancing mass

• Tumor of middle age and elderly

Central neurocytoma

• Well defined, variably vascularized lobulated mass

• Origin near foramen of Monro or septum pellucidum

• Necrosis and cyst formation are common

• Seen in young adults

Supratentorial PNET

• May exophytically extend into ventricle

• Lack of peritumoral edema

• Highly cellular tumor, isointense ~ slightly

hyperintense on T2WI

Axial FLAIRMR shows

hyperintense bilateral

subependymal giant cell

tumors (arrows). Also note

the hyperintense

parenchymal tubers

common to tuberous

sclerosis complex (open

arrows).

Coronal T2WI MR shows a mixed

signal intensity

subependymal giant cell

tumor. In addition to

obstructive hydrocephalus,

note the bosselated tumor

margins that mimic a choroid

plexus tumor (arrow).

Ganglioglioma • Cortically based hemispheric mass, solid/cystic or solid

• Mural nodule typical, often not adjacent to meninges

• Variable enhancement, no enhancing dural "tail"

• Ca++ is common; may remodel calvarium

Pilocytic astrocytoma • Supratentorial location other than hypothalamus/chiasm rare

• Typically solid and cystic or solid mass

• Enhancement but no dural "tail"

Dysembryoplastic neuroepithelial tumor(DNET)

• Superficial cortical tumor, well demarcated

• Multicystic "bubbly" ,appearance

• T2 hyperintense mass with rare, mild enhancement

• May remodel calvarium

Oligodendroglioma • Heterogeneous, Ca++ mass

• Typically larger and more diffuse than PXA

• May remodel/erode calvarium

Meningioma • Diffusely enhancing dural-based mass with dural "tail"

• Usually older patients

Low grade astrocytoma (Grade II) • Demarcated but infiltrative white matter mass

• No enhancement

Low signal in T1

High signal in T2

Low signal in T1

High signal in T2

Low signal in T1

High signal in T2 T1 with contrast

No enhancement

Low signal in T1

High signal in T2

T1 with contrast

No enhancement High signal in Flair

Anaplastic astrocytoma (M) • Hemispheric WM lesion, usually non enhancing

• Focal or diffuse mass

• May be indistinguishable without biopsy

Ischemia • Vascular territory (MCA, ACA, PCA), acute onset

• Diffusion restriction (acute/early subacute)

• Often wedge-shaped, involves GM & WM

Cerebritis • Edema, patchy enhancement characteristic

• Usually shows restricted diffusion

• Typically more acute onset

Oligodendroglioma

• Cortically-based mass with variable

enhancement

• Ca++ common

• May be indistinguishable

Herpes encephalitis

• Confined to limbic system, temporal lobes

• Hemorrhage and enhancement common

• Acute onset

Herpes encephalitis

• Confined to limbic system, temporal lobes

• Hemorrhage and enhancement common

• Acute onset

Status epilepticus

• Active seizures may cause signal

abnormalities and

enhancement

• Clinical history of seizures

Low signal in T1

High signal in T2

Patchy enhancement

report

Anaplastic oligodendroglioma (AD)

• May require biopsy to distinguish

• PET can be helpful

Astrocytoma

• Calcification less common

• Usually involve white matter, cortex

relatively spared

• May be indistinguishable

Ganglioglioma

• Usually temporal lobe, cortical

• Sharply demarcated, commonly cystic

with enhancing

nodule; Ca++ common

• Childhood, young adult tumor

Dysembryoplastic neuroepithelial tumor

(DNET)

• Sharply demarcated cortical neoplasm

• Heterogeneous, "bubbly" appearance

• Variable enhancement

• Childhood, young adult tumor

Pleomorphic xanthoastrocytoma (PXA)

• Supratentorial cortical mass, dural "tail"

common

• Often cyst and mural nodule, may be

solid

• Enhancing nodule abuts pial surface

• Childhood, young adult tumor

Cerebritis

• T2 hyperintensity and patchy enhancement

• Diffusion restriction typical

Ischemia

• Typical vascular distribution (MCA, ACA, PCA)

• Diffusion restriction if acute/subacute

• Involves GM and WM, often wedge-shaped

• Cortical, gyriform enhancement if subacute

Arteriovenous malformation (AVM)

• Typically multiple enlarged flow voids

• Often calcified

• If thrombosed, may be indistinguishable

Herpes encephalitis

• Confined to limbic system, temporal lobes

• Blood products and enhancement common

• Acute onset is typical