Central nervous sytem neoplasms and tumor-like masses Flashcards
how many % of the CNS neoplasms are malignant
32%
most of the malignanct CNS neoplasms are
glioblastoma
most of the non malignant CNS neoplasms are
meningiomas
headaches occur even though there is lack of pain receptors in the brain
there are nociceptors in the meninges and vessels, which are sensitive to stretch and therefore to any changes in ICP
headaches from neoplasm are usually worse at what position
supine
headaches from neoplasm are more commonly associated with intracranial hypotension or hypertension?
hypertension
neuroepithelial tumors cell of origin
astrocytic, oligodendroglial, ependymal, choroid plexus, neuronal, pineal, embryonal
peripheral nerve tumors cell of origin
nerve sheath (schwannoma)
meningeal tumors cell of origin
meningothelial, mesenchymal, melanocytic
hematopoietic tumors cell of origin
lymphocytic, histiocytic
germ cell tumors cell of origin
germ cells, such as germinoma
sellar region tumors cell of origin
craniopharyngioma
non invasive marker of tumor vascularity, utilized in MR perfusion
cerebral blood volume
noncontrast technique that magnetically labels arterial blood water flowing into the region of interest
arterial spin labelling
measures chemical shift of nonwater molecules in a region of interest (single or multi voxel) as a noninvasive marker of tumor metabolism
spectroscopy
main metabolites peak in the brain
choline at 3.2 ppm, creatine at 3.0 ppm, NAA at 2.0 ppm
choline/creatine ratio of ___ is suggestive of high-grade tumor
> 2
PET is less sensitive inside the CNS because
due to a high natural background uptake of glucose by normal brain tissue, especially gray matter
PET may be useful in the CNS in certain circumstance, such as
distinguishing residual/recurrent tumor from radiation-induced changes in the white matter
alternative radiotracers used in PET aside from FDG
C-11 methionine
description of a mass
should be expansile, demonstrate volume gain, displace normal brain structures
metabolite marker for astrocytes
myoinositol (3.5), decreased with higher grade
metabolite marker for cellularity
choline (3.2), increased with higher grade
metabolite marker of energy
creatine (3.0), decreased with higher grade tumors
metabolite marker of hypoxia
lactate (1.3) increased with higher tumor grade
metabolite marker of necrosis
lipids (0.9 - 1.4), increased with higher grade
intra-axial mass means
pia mater, including both the parenchymal and ventricular comparetments, paralelling the use of “intramedullary” in the spinal cord
extra-axial masses are characterized by
“white matter buckling”, or inward compression of the cortical gray matter and underlying white matter fronds (there may also be a visible intervening CSF cleft)
intra-axial masses are characterized by
tend to expand the white matter and thicken its fronds, with a “claw sign” of normal brain parenchyma wrapped around the margins of the mass
intratumoral hemorrhage is common in what tumors
highly vascular neoplasms such as glioblastoma or oligodendroglioma
Protrusion of an anatomic structure from its normal position
Herniation
More common form of herniation and involves partial displacement of cerebral hemispheres across the midline into the contralateral cranial component
Subfalcine herniation
When subfalcine herniation is severe, it can compress or compromise what vessel
Anterior cerebral arteries
Less common form of herniation and involves the partial displacement of the medial temporal lobe into the basal cisterns and tentorial hiatus
Uncal herniation
When uncal herniation is severe, it can compress what structures
Ipsilateral posterior cerebral artery, contralateral midbrain, ipsilateral oculomotor nerve (“blown pupil”)
form of hydrocephalus seen with tumor locations that can obstruct CSF flow within the ventricular system, for example, near the foramen of Monro or the aqueduct of Sylvius
noncommunicating hydrocephalus
form of hydrocephalus that is seen with diseases that interfere with CSF reabsorption at the arachnoid granulations and less commonly with choroid plexus tumors that can cause CSF overproduction
communicating hydrocephalus
intra-axial tumors are commonly neuroepithelial or non neuroepithelial
neuroepithelial
extra-axial tumors are commonly neuroepithelial or non neuroepithelial
non neuroepithelial
examples of nonenhancing intra-axial mass
diffuse astrocytoma, oligodendroglioma
examples of enhancing intra-axial mass
glioblastoma, metastases
examples of enhancing intra-axial mass in child
pilocytic astrocytoma, embryonal tumors
examples of hyperattenuating intra-axial mass
primary cns lymphoma, embryonal tumors,
examples of cortical masses
DNET, Ganglioglioma
examples of ventricular masses
ependymal tumors, central neurocytoma
choroid plexus masses
choroid plexus tumors, meningioma
pineal region masses
pineal parenchymal tumors, germ cell tumors
characterized by high nucleus-to-cytoplasm ratios and lower free water content, which results in lower signal intensity on T2 and ADC images
hypercellular neoplasms
high SI in T1 usually indicates the presence of
fat (lipids), blood (methemoglobin) or protein
hemorrhagic metastases (MR CT BB)
melanoma, renal cell ca, choriocarcinoma, thyroid carcinoma, breast carcinoma, bronchogenic carcinoma
calcified intracranial masses (CA COME)
craniopharyngioma, astrocytoma, aneurysm, choroid plexus tumor, oligodendroglioma, meningioma, ependymoma
parenchymal enhancement is an indicator of
the integrity of blood brain barrier
parenchymal enhancement in neoplasm indicates
fenestrated capillaries in low grade tumors or high-grade microvascular proliferation
vascularized granulation tissue develops within how many hours following surgery and enhances after administration of contrast
48 to 72 hours
in post-op imaging of brain tumor, it must be obtained within 48 to 72 hours post op using MRI because
to minimize the formation of reactive granulation tissue, which can be confused for residual tumor
current standard therapy for glioblastoma is
Stupp protocol: maximal safe resection, followed by fractionated radiation and temozolomide chemo for 6 weeks, followed by adjuvant temozolomide for 6 cycles/months
term for a transient radiation-induced enhancing lesions that appears during treatment of glioblastoma, less than 6 months after radiation, difficult to distinguish from true progression
pseuoprogression
term for a more severe permanent tissue injury that happens later, months to years postradiation
radiation necrosis
75% of all gliomas are
astrocytoma
major groups of astrocytomas and gliomas based on growth pattern
circumscribed and diffuse
type of gliomas that demonstrate more well-defined margins on microscopic examination and tend to be more amenable to a surgical care
circumscribed
type of gliomas that demonstrate more ill-defined margins on microscopic examination, regardless of the macroscopic appearance on cross-sectional imaging
diffuse or infiltrative gliomas
most common pediatric CNS tumor
pilocytic astrocytoma
most common location of pilocytic astrocytoma
cerebellum 60%, optic pathways/hypothalamus 30%, brainstem
pilocytic astrocytoma is associated with
NF1 and found in 15% of optic gliomas
less common and more aggressive variant of pilocytic astrocytoma
pilomyxoid astrocytoma
pilomyxoid astrocytoma is commonly seen in
suprasellar region
it is a slow growing tumor located at the foracmen of monro and is associated with tuberous sclerosis
subependymal giant cell astrocytoma
peripherally located cerebral tumor that often involves the cortex/meninges
pleomorphic xanthoastrocytoma
classic presentation of pilocytic astrocytoma
nonenhancing cyst with enhancing mural nodule in the cerebellum
diffuse gliomas are subdivided into
isocitrate dehydrogenase mutant versus wildtype
majority of diffuse and anaplastic astrocytomas are
IDH mutant
presents as an expansile parenchymal lesions, hypodense on CT and hyperintense on T2, without significant enahncement (intact BBB). these are also commonly seen in older age (>40 years), imaging markers of increased cellularity (decreased diffusion), mitotic activity (increased choline) or tumor vascularity (increased perfusion)
low-grade diffuse astrocytoma and high-grade anaplastic astrocytoma
most common primary intra-axial tumor of CNS
glioblastoma
vast majority of glioblastoma are
IDH-wildtype
other molecular marker of glioblastoma
methylation (inactivation) of the gene promoter for O6-methylguanine DNA methyltransferase repair enzyme (MGMT) that counteracts the effects of temozolomide chemotherapy
these tumors typically presents as a heterogeneous enhancing parenchymal mass with surrounding vasogenic edema
glioblastoma
difference of ring enhancement between glioblastoma and abscess
thick and irregular, with restricted diffusion- glioblastoma
thin and smooth- abscess
incomplete ring of enhancement (“horseshoe” or “open ring” sign) should prompt consideration of a
tumefactive demyelinating lesion, rather thatn neoplasm or abscess
ring enhancing lesions (MAGIC DR)
metastasis, abscess, glioma (esp glioblastoma),infarct (subacute or healing phase), contusion/hematoma (subacute), demyelinating disease, radiation necrosis
diffuse or infiltrative glioma that crosses the corpus callosum to involve both cerebral hemispheres
butterfly glioma
expansile lesion within the corpus callosum cannot be attributed to vasogenic edema, because
callosal fibers are too tightly packed for the interstitial fluid to be transmitted across them
low grade brainstem gliomas are seen in
midbrain
diffuse infiltrative glioma in young children with highly aggressive behavior are usually seen in ____, despite absent or minimal enhancement
pons
describes the widespread infiltrative growth of a diffuse glioma, more commonly astrocytoma than oligodendroglioma, to involve at least 3 lobes of the brain
gliomatosis cerebri
demosntrates a diffuse growth pattern, just like their astrocytic counterparts, with neoplastic cells infiltrating beyond the macroscopic margins of the tumor. these cells have a “fried egg” appearance due to round nuclei surrounded by clear cytoplasm. additional histologic features include microcalcifications and a dense network of branching capillaries ( chicken wire)
oligodendrogliomas
types of oligodendrogliomas
IDH mutated and 1p/19q codeleted
presents as an expansile infiltrative parenchymal lesion, typically hypodense on CT and hyperintense on T2. most commonly located in the frontal lobes and often extend peripherally to involve the cortex. more likely to exhibit calcifications on CT, more vascular
oligodendrogliomas
codeleted 1p/19q chromosome show more or less favorable prognosis?
more favorable
intact 1p/19q chromosome show more or less favorable prognosis?
less favorable
methylated MGMT gene promotor show more or less favorable prognosis?
more favorable
accounts of approximately 7% of all gliomas, tends to present in the pediatric population. arise form the ependymal cells lining the ventricular system and the central canal of the spinal cord. often presents as a fourth ventricular mass in children, less commonly as an intramedullary mass in adults
ependymomas
true or false: ependymomas tend to originate within the brain parenchyma rather than in the lateral-third ventricles when they present supratentorially
true
supratentorial ependymomas are classified as
ependymoma, RELA fusion positive
tumors that present as perivascular pseudorosettes histologically
ependymoma
typically pressents are heterogeneous enhancing mass with calcifcation, cystic change and/or hemorrhage within the 4th ventricle in a child. they are soft plastic tumors that frequently extrude out of the foramina of Luschka laterally or Magendie inferiorly
ependymoma
tumor that arises from underneath the ependymal lining of ventricular system that lies a thin subependymal glial plate
subependymoma
most common locations of subependymoma
inferior fourth ventricle, lateral-third ventricle, spinal cord
formed embryologically by invagination of leptomeninges into the lateral ventricles through the choroidal fissure, choroid plexus epithelum and stroma
choroid plexus
choroid plexus epithelium are derived from
ependymal cells
stroma are derived from
arachnoid mater
intensely enhancing mass with lobulated margins that are usually centered at the atrium or trigone of the lateral ventricle, arising from the choroid plexus glomus and less commonly in the 4th ventricle
choroid plexus tumors
nonglial tumors of neuroepithelial origin include
neuronal tumors, embryonal tumors and pineal tumors
nonglial tumors that are rare, with varying degress of neuronal differentiation
neuronal and mixed-neuronal-glial tumors
benign mixed neuronal-glial (aka glioneuronal) tumor with excellent prognosis, associated with medically refractory partial complex seizures in children and young adults
dysembyoplastic neuroepithelial tumors (DNET)
identified histologically by presence of cortical dysplasia and columns of bundled axons lined with oligodendroglial-like cells (“specific glioneuronal unit”). there are cortical neurons “floating” in a mucinous background
dysembryoplastic neuroepithelial tumors
tumors that appears nonenhancing multicystic (“bubbly”) mass at the cerebral cortex in a young patient, usually at the temporal lobe
dysembryoplastic neuroepithelial tumors
pure neuronal tumor composed of neoplastic gangliomn cells
gangliocytoma
mixed glioneuronal tumor with neoplastic glial cells
ganglioglioma
typical imaging pattern is a partially enhancing mass at the cerebral cortex in a young patient. it is the most common neoplastic etiology for temporal lobe epilepsy
gangliocytoma and ganglioglioma
true or false: gangliocytoma and ganglioglioma may arise from gray matter anywhere within the CNS, including hypothalamus, cerebellum and spinal cord
true
usually present in young adults with symptoms related to local mass effect. classic imaging pattern is nonenhancing mass that expands the cerebellar folia and causes a “striated cerebellum” appearance on MRI. frequently associated with Cowden syndrome
Dysplastic cerebellar gangliocytoma (Lhermitte-Duclos Disease)
they can present as a heterogeneous mixed-cystic-solid mass (“cyst and nodule” appearance) involving te cerebral cortex. it may cause desmoplastic reaction with thickening and enhancement of overlying meninges, analogous to PXA. they tend to present in infancy with rapidly progressive macrocephaly
desmoplastic infantile astrocytoma and ganglioglioma (DIA and DIG)
rare grade 1 tumors with mixed glial and neuronal elements
papillary glioneuronal tumor (PGNT) and rosette forming glioneuronal tumor (RGNT)
in this tumor, the glial cells form a pseudopapillary arrangement with interpapillary neuronal cells. it presents as a cerebral mixed solid-cysitc mass with predilection for the temporal lobe, similar to ganglioglioma
papillary glioneuronal tumor
in this tumor, glial component resembles a pilocytic astrocytoma, while neuronal component forms neurocytic rosettes and perivascular pseudorosettes. it also presents as a mixed cystic-solid mass, but is most commonly located in the middle, around the fourth ventricle or the cerebral aqueduct
Rosette-forming glioneuronal tumor
ventricular tumor of unclear cell origin. histologically, they can resemble oligodendrocytes, hence these tumors were initially mistaken for intraventricular oligodendrogliomas
central neurocytoma
common in 20 to 40 y.o as an intensely enhancing mass arising from the septum pellucidum or lateral ventricular wall, near the foramen of monro. On T2, they gave a heterogeneous appearance (“bubbly”)
central neurocytoma
histologically similar tumor to central neurocytoma that occurs in the brain parenchyma
extraventricular neurocytoma
highly malignant tumors of neuroepithelial origin, which are too poorly differentiated to be categorized as glial or neuronal tumors. tend to appear as hypercellular hyperattenuating masses in children (age <20 y.o)
embryonal tumors
most common CNS embryonal tumor as well as the second most common pediatric CNS tumor. it is a critical member of pediatric posterior fossa differential diagnosis. arise from the cerebellar vermis in children less than 10 y.o
medulloblastoma
when medulloblastoma arise in older children and adults, they have a tendency to be located where
within the cerebellar hemisphere
four histologic subtypes of medulloblastoma
classic, desmoplastic/nodular, medulloblastoma with extensive nodularity (MBEN) and large cell/anaplastic
histologic subtype of medulloblastoma that most likely show CSF dissemination, seen in a third of medulloblastoma
large cell/anaplastic
classically presents as hyperdense mass at the cerebellar vermis in a young child
medulloblastoma
pediatric fossa tumors (GAME)
brainstem glioma, pilocystic astrocytoma, medulloblastoma, ependymoma
these are 1/3 of emryonal tumors, that can present as a heterogeneous hyperattenuating mass anywhere in the CNS, usually in infants or very young children (<4 y.o). genetically defined by alterations of INI1, which can be tested by immunohistochemistry
atypical teratoid/rhabdoid tumor (AT/RT)
when cases do not meet criteria for medulloblastoma, AT/RT or other defined entities, “CNS embryonal tumor, not otherwise specified (NOS)” has replaced ____ as a new moniker
CNS primitive neuroectodermal tumor (PNET)
most common primary intra-axial posterior fossa mass of adulthood, usually presenting in middle age (40-60 years)
hemangioblastoma
they are circumscirbed enhancing tumors that can secrete fluid and produce internal or adjacent cysts. it has increased vascularity
hemangioblastomas
fewer that 10% of hemangioblastomas arise outside the posterior fossa, often in the setting of
Von Hippel Lindau syndrome
histologic subtype of medulloblastoma with classic histology, best prognosis, seen in the lateral location (peduncle)
WNT activated
histologic subtypes of medulloblastoma with classic or large cell/anaplastic histology that is midline in location (vermis) with poor prognosis
SHH-activated TP53-mutant, “group 3” and “group 4”
histologic subtype of medulloblastoma with desmoplastic/nodular, MBEN histology, lateral in location (hemisphere), with good prognosis
SHH-activated TP53-wildtype
most common non-hodgkin lymphoma of adults and can arise in vitually any compartment of the body, including the brain parenchyma
Diffuse large B-cell lymphoma
Primary CNS lymphoma is tx by
chemotherapy
this drug can shrink the PCNSL tumor transiently and sometimes dramatically (“ghost tumor”, withholding steroid therapy before biopsy may help to maximize sensitivity
glucocorticoids
in immunocompetent patient, classic imaging pattern of this tumor is a homogeneously enhancing mass that abuts the CSF spaces and wraps around the ventricles or sulci (“rimphoma”) with homogeneous hyperdensity on CT and corresponding hypointensity on T2/ADC
PCNSL
50% of brain metastasesm are secondary to
lung cancer
leptomeningeal metastasis from a primary CNS tumor is called
drop metastases
responsible for myelination in the CNS
oligodendrocytes
responsible for myelination in the peripheral nerves including cranial nerves III to XII
schwann cells
these are benign extra-axial neoplasms which arise from vestibular nerve in the vast majority of the cases
schwannoma
schwannoma can also less commonly involve what cranial nerve and other areas
CN5, brain parenchyma, peripheral nerves that innervate vessel walls (nervi vasorum)
these are focal encapsulated tumors with spindle-saped neoplastic schwann cells on histopathology, which may be organized in a more cellular Antoni A pattern with nuclear palisading (“Verocay bodies”), versus a less cellular Antoni B pattern with cystic degeneration (“ancient change”)
schwannoma
tumor that often arise within and gradually expand the bony internal auditory canal, while growing medially into the CPA cistern, yielding an “ice cream cone” appearance
schwannoma
it is a misnomer and is characterized by multiple schwannomas and meningiomas, not neurofibromas
NF2 and schwannomatosis
bilateral vestibular schwannomas are diagnostic of
NF2
Schwannomatosis is associated with mutations in what tumor marker
SMARCB1 tumor suppresor gene
most common extra-axial tumors and also the most common primary CNS tumors (36%). more freq in females, present in older adults. they arise from arachnoid cap cells in the arachnoid mater, which abuts the dura mater on the side of the skull. half of the cases present as dural-based masses along the cerebral convexity or the falx cerebri (parasagitta)
meningioma
classic, but nonspecific appearance of a meningioma is
enchancing dural-based mass, with adjacent dural thickening and osseous changes
if angiography is performed as a work-up for meningioma (pre-operative emblozation), there is radial arrangement of the vessels with an early dense tumor blush that persists well into venous phase. this angiographic finding has been called ____ because it shows up early and stays late
“mother in law sign”
it is not uncommon for a meningioma to evoke vasogenic edema in the adjacent brain parenchyma, especially when it is supplied by what vessel; this alone is not a sign of brain invasion or higher-grade tumor
ICA rather than ECA
CPA mass (AMEN)
arachnoid cyst, meningioma, epidermoid cyst, neuroma /schwannoma
an avidly enhancing mass located in the atrium/trigone of a lateral ventricle should prompt consideration of _____ in a child and ____ in an older adult
choroid plexus papilloma in child, intraventricula meningioma in older adult
dural-based meningothelial mass
meningioma
mesenchymal dural based mass
hemangiopericytoma
metastatic dural-based mass
breast, prostate, lung
hematopoietic dural-based mass
leukemia, lymphoma
inflammatory, dural based mass
sarcoidosis, TB
previously known as “angioblastic meningioma”. it arises from modified pericapillary smooth muscle cells (pericytes of Zimmerman) with peak incidence at 30-50 years
hemangiopericytoma
histologic examination of this tumor show “staghorn vessels”
hemangiopericytoma
unlike meningioma, these tumors show a narrow base of attachment to the dura in 33% of cases
hemangiopericytoma
between meningioma and hemangiopericytoma, bone destruction and flow void are more common in
hemangiopericytoma
hyperostosis and calcifications are more common in meningioma or hemangiopericytoma
meningioma
elevated myoinositol can be seen in hemangiopericytoma or meningioma
hemangiopericytoma
alanine peak is seen in hemangiopericytoma or meningioma
meningioma
tumor from ependymal lining
ependymoma
tumor from central neurocytoma
septum pellucidum
tumor from subependymal plate
subependymoma
tumor from choroid plexus epithelium
choroid plexus tumor
tumor from choroid plexus stroma
meningioma and metastasis
meningeal melanocytoma and melanoma can be seen where
leptomeninges, uvea of the eye
small usually subcentimeter “pine-cone”- shaped structure which has been historically described as the “third eye” or the principal seat of soul
pineal gland
it is an endocrine organ that secretes melatonin into the bloodstream, therefore it lacks blood-brain barrier and normally enhances on post contrast images
pineal gland
pineal gland is located in the
midline, at the posterior margin of 3rd ventricle, just below the splenium of the corpus callosum and just above the tectum of midbrain
circumscribed slow growing pineal tumors that tend to present in adults with symptoms related to local mass effect. they can be cystic or solid in morphology
pineocytoma
more atypical aggressive lobulated enahncing pineal masses that also tend to present in adults
pineal parenchymal tumor of intermediate differentiation (PPTID)
highly malignant undifferentiated embryonal tumors of the pineal gland that tend to present in children. they are enhancing and hypercellular in appearance, for example, hyperdense on CT and hypointense on T2/ADC
pineoblastoma
most common type of neoplasm in the peineal region
germ cell tumor
most common intracranial GCTs and have a strong preference for males over females. they are hypercellular with sheets of polygonal germ cells and may be complicated by CSF dissemination
germinoma
tends to wrap around or engulf normal pineal calcifciations
germinoma
these pineal gland tumor tend to displace or “explode” calcifications
pineal parenchymal tumor
primary treatment modality for germinomas
radiation
a heterogeneous midline mass in a newborn should prompt consideration of a
congenital teratoma
other tumors that can project into the pineal region include ____ and ____ arising from the splenium superiorly or tectum inferiorly. there is also from the subcommissural organ
tentorial meningioma and exophytic gliomas, papillary tumor of the pineal region
midline depression at the top of sphenoid body that holds the pituitary gland. aka turkish saddle
sella turcica
sella turcica is separated from the suprasellar cistern superiorly by the _____
diaphragm sellae
with aging, the diaphragm sellae can weaken and permit subarachnoid space to herniate inferiorly from the suprasellar cistern in the sella turcica, making this appearance
empty sella appearance
pituitary stalk and posterior pituitary are derived from
neuroectoderm and are extensions of diencephalon
anterior pituitary is derived from
surface ectoderm, specifically from primitive stomodeum
during development, primitive stomodeum from surface extoderm forms an epithelial diverticulum, aka ____ or _____, which extends from the pharynx into the cranial vault to meet the neurohypophysis and form the adenohypophysis anteriorly
craniopharyngeal dyct or Rathke pouch
one of the 3 most common primary neoplasms, not listed in the CNS WHO classifcations (considered endocrine)
pituitary adenomas
3 most common primary CNS neoplasms
meningiomas (36%), adenomas (16%), glioblastoma (15%)
microadenomas measure
< 1cm
macroadenomas meaure
> 1 cm
most common pituitary adenoma that may produce amenorrhea/galactorrhea in women or decreased libido in men
prolactinoma
second most common pituitary adenoma and may produce acromegaly or gigantism
GH-secreting adenomas
this adenoma may cause symptoms from local mass effect. usually the primary concern is visual loss from compression of the optic nerves, chiasm or tracts superiorly
macroadenomas
compression of the pituitary gland or stalk may produce
hypopituitarism or hyperprolactinemia
most pituitary adenomas will arise ___, because lactotrophs and somatotrophs are located also here
laterally
when pituitary macroadenoma suddenly enlarges due to hemorrhage, this acute syndrome is called
pituitary apoplexy
arise from squamous epithelium remnants of the craniopharyngeal duct, aka Rathke pouch. it can occur anywhere between nasopharynx, 3rd ventricle, but is most commonly centered in the suprasellar region
craniopharyngioma
most common neuroepithelal CNS tumor of childhood. they are characterized by heterogeniety as described by 90% rule: 905 show cystic change, show calcifications and show solid or nodular enhancement
adamantinomatous craniopharyngiomas
nonneoplastic cysts that result from a persisten cleft in the Rathke pouch that fails to involute
Rathke cleft cysts
less common type of craniopharyngioma that occurs in older adults as a solid enhancing mass
papillary craniopharyngioma
rare neuroendocrine tumor of the adenohypohysis that closely resembles a nonfunctioning macroadenoma
spindle cell oncocytoma
these are rare glial tumors that arise from the neurohypophysis or infundibulum
pituicytoma and granular cell tumor
suprasellar masses (SATCHMO)
sarcoidosis, adenoma/aneuryms, teratoma/germinoma, TB, craniopharyngioma, rathke cleft cyst, hypothalamic glioma, hamartoma, histiocytosis, meningioma, metastasis, optic pathway glioma
thin-walled meningothelial cysts located in the arachnoid space and are thought to result from a congenital duplication or splitting of the embryonic arachnoid during development
arachnoid cysts
acquired arachnoid cysts may be from
chronic sequelae of prior inflammation
50% of arachnoid cysts are seen in the
middle cranial fossa
difference between epidermoid and dermoid cyts
epidermoid cyst resemble CSF density and signal, except for marked hyperintensity on DWI, dermoid cyst can present with internal fat density and signal due to sebum, no solid enhancement
accidental rupture or spillage of the dermoid cyst may cause
chemical meningitis
benign, slow growing cysts, lined by squamous epithelium that produces large amounts of keratin. they arise from abnormal inclusion of surface or external ectoderm that can produce cyst with lining that resemble norml skin epithelium
epidermoid and dermoid cysts
epidermoids are more located ___, while dermoids are ____
epidermoids lateral, dermoids midline
how to differentiate epidermoid cyst from arachnoid cyst
epidermoid cysts show restricted diffusion
rarely, epidermoids can be highly proteinaceous and demonstrate an atypical appearance on CT (hyoerdense) or MRI (T1 hyperintense); this atypical presentation is called
white epidermoid
endodermal inclusion cysts, whose lining resemble bronchial or respiratory epithelium, hencethey are filled with mucin and are highly proteinaceous
colloid cysts
colloid cysts are found at ____, where they can cause acute hydrocephalus and sudden death
anterosuperior roof of the 3rd ventricle near the foramen of Monro
these cysts may present chronically with paroxysmal headaches and /or neurologic deficits, excacerbated by tilting the head forward (Brun phenomenon), due to ball-valve action of the cyst
colloid cysts
nonneoplastic masses of true adipose tissue that result from maldifferentiation of the embryonic meninx primitiva into fat rather than normal subarachnoid space. most common in interhemispheric fissure (probably associated with callosal dysgenesis), suprasellar cisterna dn quadrigeminal cistern
lipomas
ectopic nodules of misplaced neurons due to arrested migration during development. these clumps can be mistaken for tumor and are most often found in a periventricular or subependymal location
gray matter heterotopia
when gray matter heterotopia is seen in the hypothalamus, usually the tuber cinereum between the optic chiasm and mammillary bodies, it is often called
hamartoma
these lesions may present with unusual symptoms such as gelastic seizures (laughing fits) or precocious puberty
hamartoma of tuber cinereum
