Tumors Flashcards
MC extra-axial neoplasm of the brain?
meningioma
What percentage of meningiomas occur supratentorially?
90%
MC locations for meningioma outside of the CNS?
sinonasal cavity, parotid gland, deep (neck) tissues, skin
CT characteristics of meningioma?
60% are hyperdense, 20% have calcification.
What is the “cleft” sign?
The “cleft sign” has been described in MR to identify extra-axial intradural lesions such as meningiomas. The cleft usually contains one or more of the following: (1) cerebrospinal fluid (CSF) between the lesion and the underlying brain parenchyma, (2) hypointense dura (made of fibrous tissue), and (3) marginal blood vessels trapped between the lesion and the brain.
How often do meningiomas show a “dural tail”?
72% of the time
Top differential considerations for a meningioma?
the typical situation is a differential diagnosis of vestibular schwannoma, or fifth nerve schwannoma
Intraosseous menengioma may resemble what other neoplastic process?
Blastic osseous mets
Intraventricular meningiomas typically occur where?
Intraventricular meningiomas typically occur around the choroid plexus (80%) in the trigone of the lateral ventricle and have a distinct propensity for the left lateral ventricle
Intraventricular meningiomas calcify how often and in what age group are they more often found?
Intraventricular meningiomas calcify in 45% to 68% of cases, and their frequency is higher in children
Multiple meningiomas are associated with what?
neurofibromatosis type 2
How often are bony changes seen with meningioma, and where?
20% to 46% of cases. Hyperostosis is particularly common when the tumor is at the skull base or
anterior cranial fossa, and here it may resemble fibrous dysplasia or Paget disease.
Role of angiography and appearance with meningioma?
Meningiomas diagnostically appear as lesions with an angiographic stain (tumor blush) and have both dural and pial blood supply.
The characteristics of the stain are classically compared with an unwanted guest who comes early
and stays late.
Features of malignant meningioma?
usually diagnosed when a meningioma exhibits intraparenchymal invasion or markedly rapid growth have restricted diffusion compared to benign meningiomas.
Are hemangiopericytomas more common in men or women?
Men, unlike most meningiomas which are more common in women.
Location of hemangiopericytomas?
They tend to be large (over 4 cm in size), lobular, and extra-axial supratentorial masses. Hydrocephalus, edema, and mass effect are not uncommon with this entrée.
Features of melanocytoma?
usually presents as a posterior fossa mass. Hyperintensity on T1WI is the only hope for sealing this
diagnosis, but the presence of this finding varies with melanin content. Spread of melanocytosis through the Virchow-Robin spaces is possible.
What are “the three” neurogenic tumors?
schwannomas, neurofibromas, and neuromas - all similar in appearance
What finding is associated with vestibular schwannomas 7-10% of the time?
arachnoid cyst
Schwannoma or Meningioma brighter on T2?
Schwannoma much more often than Meningioma. (due to cysts and/or Antoni B tissue)
Important finding in schwanoma not seen in meningioma related to effect on adjacent bony structure?
The porus acusticus (the bony opening of the IAC to the cerebellopontine angle cistern) is typically flared and enlarged with vestibular schwannomas, whereas the amount of tissue seen in the IAC with meningiomas is usually small or absent.
Top differential for a jugular foramen tumor? How do you differentiae the two?
Jugular schwannomas more commonly grow intracranially than extracranially and typically smoothly erode the jugular foramen. The border of the bone is sclerotic, as opposed to the paraganglioma, which has a much more irregular and nonsclerotic margin. Schwannomas compress the jugular vein, whereas paragangliomas (glomus jugulare tumors) invade the vein. Growth into the posterior fossa is the rule.
What are nueromas and where do they occur?
By strict pathologic definition neuromas refer to a posttraumatic proliferation of nerve cells rather than a true neoplasm. They are usually seen in the cervical spine when nerves are avulsed or in an operative bed.
What primarys cause dural metastases?
Lung, breast (MC), and prostate cancer, as well as
melanoma, are known to produce dural metastases. Lymphoma too, but may be primary in the dura
In children dural metastases are most commonly associated with what primary?
adrenal neuroblastomas and leukemia.
Inflammatory lesions that may simulate dural metastases?
granulomatous infections (mycobacterial, syphilitic, and fungal), Erdheim-Chester disease, sarcoidosis, and Langerhans cell histiocytosis.
Apprearance of subarachnoid seeding?
Usually one sees tiny nodules of implanted tumor seedings.
When subarachnoid seeding is diffuse it is termed what?
“sugarcoating” of the subarachnoid space because the whole pial surface is studded with sugar granules.
most common tumors to seed the CSF?
Lymphoma and leukemia
(However, because they only rarely invade the meninges and do not incite reactions in the CNS, lymphomatous clusters are infrequently identified by neuroimaging techniques; the diagnosis is usually made by multiple spinal taps for CSF sampling)
What is the appearance of CSF on FLAIR with malignant involvement?
The malignant cells in the CSF or the associated elevated protein in the CSF will cause the usually low signal of CSF to be bright on a FLAIR scan. Although this may be a difficult diagnosis to make in the basal cisterns where “f ” (FLAIR and flow) artifacts abound, the presence of such high signal over the convexities implies subachnoid seeding, subarachnoid hemorrhage, or meningeal inflammation. FLAIR may even be positive in lymphoma and leukemia, where enhanced scans fail most dramatically. FLAIR
with contrast enhancement increases the yield even higher!
AKA’s for subarachnoid seeding?
meningeal carcinomatosis or carcinomatous meningitis.
What is a chloroma?
Granulocytic sarcoma (chloroma) is a tumor of immature granulocytes found in association with myelogenous leukemias. This soft-tissue mass can occur virtually anywhere and may predate the diagnosis of leukemia. In the CNS, the orbit and epidural space are affected most commonly, The term chloroma refers to its greenish color akin to chlorophyl. Chloromas portend a blast crisis.
Common location for choroid plexus papilloma in adults?
4th ventricle
This tumor compromises 10-20% of intracranial tumors presenting in the first year of life.
choroid plexus papilloma
Presentation of choroid plexus papilloma?
The tumors present with hydrocephalus and papilledema caused by overproduction of CSF (four to five times normal) or obstructive hydrocephalus caused by tumor, hemorrhage, high-protein CSF, or adhesions obstructing the ventricular outlets.
Apprearance of choroid plexus papilloma?
Choroid papillomas are typically hyperdense on unenhanced CT, with a mulberry appearance. Tumors are usually of low signal on T1WI and mixed intensity on
T2WI unless hemorrhage has occurred. These tumors enhance dramatically .
(Calcification occurs in 20% to 25% of cases, and hemorrhage in the tumor is seen even more frequently than calcification.)
Contents of an epidermoid?
Epidermoids are collections of epithelium with desquamated debris (keratin and cholesterin) resulting from inclusion of ectodermal rests at the time of neural tube closure early in embryonic development.
Epidermoids may resemble what other lesion on CT?
Sometimes epidermoids are hard to distinguish from arachnoid cysts, particularly
in the cerebellopontine angle cistern. They are low density, similar to CSF.
How do you differentiate epidermoids and arachnoid cysts on MR?
epidermoids are bright on FLAIR, whereas arachnoid cysts are as
dark as CSF. Otherwise they look the same on T1/2. On DWI these lesions are usually very bright and easily distinguishable from arachnoid cysts, which are dark on DWI.
Appearance of dermoid on MR?
The high intensity of fat and signal void of calcification on T1WI suggests a diagnosis of a dermoid or teratoma. These lesions more typically occur in the midline as opposed to epidermoids, which are generally off the midline. The possibility of a ruptured dermoid should be considered when multiple fat particles are seen scattered on an MR or when lipid is detected in the CSF.
Name the tumor.
A congenital benign hamartomatous lesion derived from notochord remnants, usually located in the retroclival prepontine region, but can be found anywhere from the skull base to the sacrum. Usually asymptomatic. Found in approximately 2% of autopsies.
Ecchordosis physaliphora
WHO classification of astrocytomas? (1-4)
circumscribed astrocytomas (grade I), diffuse astrocytomas (grade II), anaplastic astrocytomas (grade III), and GBM (grade IV) on the basis of histologic criteria
most common infratentorial neoplasm in the pediatric age group?
Cerebellar juvenile pilocytic astrocytomas (JPAs)
WHO grade I astrocytic tumor
Appearance of
The typical cerebellar astrocytoma in the pediatric age
group is cystic (60% to 80%), whereas in older patients it is more likely to be solid. A mural nodule may be present with a similar appearance to the hemangioblastomas of adults. The solid portion of the JPA enhances
strongly. In general, pilocytic astrocytomas are well outlined from normal brain, are usually round, and usually are not ominous in appearance.
Pleomorphic Xanthoastrocytoma typically occurs where and in whom?
<30 years. The lesion shows a preference for the periphery of the temporal lobes as they arise from subpial astrocytes. They may show a base at the meninges in more than 70% of cases.
Pleomorphic Xanthoastrocytoma are hard to distinguish
from what other tumor?
These tumors are hard to distinguish from dysembryoplastic neuroepithelial tumors. PXAs have a meningeal attachment and no cortical dysplasia, and enhance more frequently.
what astrocytoma is associated with tuberous sclerosis?
Subependymal Giant Cell Astrocytomas
Subependymal Giant Cell Astrocytomas typically occur where?
SGCAs typically occur near the foramina of Monro and, in contradistinction with tubers, demonstrate moderate to marked enhancement
Besides brain stem glioma, what other lesions may exapnd the brain stem in a child?
Other lesions that expand the brain stem in a child include tuberculosis (most common worldwide), lymphoma, rhombic encephalitis (caused by Listeria), and demyelinating disorders (acute disseminated encephalomyelitis and multiple sclerosis).
Difference between an anaplastic astrocytoma and GBM on imaging?
No necrosis in anaplastic astrocytoma. if
necrosis is seen, bump the lesion up to a GBM. ultimate
dedifferentiation into GBM occurrs in 50% of case of AA>
how does relative cerebral blood volume (rCBV) correlates with astrocytoma histology?
the higher the rCBV, the more likely one is dealing with a
GBM.
When you see a lesion involving the corpus callosum you should put what two lesions near the top of the list of
neoplasms?
GBM and lymphoma
What condition is associated withmultifocal astrocytomas.?
NF-1
This tumor commprises 50% of cerebellar
tumors in children, and is the most common paediatric posterior fossa tumour
Medulloblastoma (PNET)
incidence of calcification and cystic change in medulloblastoma?
Medulloblastomas have a 10% to 21% incidence of calcification. Cystic change, initially thought to be rare, occurs in 10% to 20% of pediatric cases and 59% to 82% of adult cases
medulloblastomas originate where typically
Vermis of cerebellum
supratentorial PNETs show calcification how often?
50-70%
Dysembryoplastic Neuroepithelial Tumor usually has what shape and is found where?
Triangular, temporal (50-62%) and frontal (31%) lobes.
On MR, this tumor is characterized by the presence of cysts, usually multiple.
“Classic” appearance of an ependymoma in the posterior fossa?
A classic appearance of a posterior fossa ependymoma is a calcified fourth ventricular mass that extends through and widens the foramina of Luschka andMagendie.
lowest grade ependymoma is found where?
filum terminale
Difference between ependymoma and subependymoma?
Subepenymomas present in late adulthood.
the most common mixed glioneural tumors of the CNS? When do they present?
Gangliogliomas. Up to 80% before 30 years of age
Gangliogliomas occur where most often?
Temporal lobes (85%)
How do you differentiate a cystic Ganglioglioma from an arachnoid cyst or epidermoid?
They are intraparenchymal
what do you call a gangliocytoma of the cerebellum? (eponym)
Lhermitte-Duclos disease
Oligodendroglioma’s are typified by what finding? Who are they found in?
high rate of calcification (40-80%)
Men 2:1, 40-50 years
gliomatosis cerebri involves how much of the brain?
At least 3 lobes
The most common primary intraparenchymal tumor in the infratentorial space in adults?
Hemangioblastomas
Hemangioblastomas occur where most often?
More than 83% of HBs occur in the cerebellum
clinical symptom attributable to Hemangioblastomas, present 40% of the time?
Polycythemia caused by increased erythropoietin production. More common with solid ones.
With what condition are Hemangioblastomas commonly associated, and how often?
25% of HBs occur in association with von Hippel-Lindau
disease (VHL).
Appearance of HB’s on MR & CT?
The stereotypical findings of an HB are those of a cystic mass with a solid mural nodule (55% to 60% of cases), which is highly vascular and has serpentine signal voids of feeding vessels. May be solid or rarely cystic. Cytic lesions will have a mural nodule demonstrates striking enhancement. The cyst and its walls do not enhance. A purely solid HB also demonstrates strong enhancement.
Best differentials for a hemorrhagic tumor?
hemorrhagic metastasis, GBM, oligodendroglioma
Signal characteristics of melanoma mets?
In the case of melanoma one can identify nonhemorrhagic melanotic metastases as lesions that have high intensity on T1WI and isointensity to hypointensity on T2WI caused by intrinsic paramagnetic effects
Breast mets that are estrogen- and progesterone receptor-negative develop mets where?
brain and meningeal but not calvarial metastases. Calvarial mets are receptor positive.
mets tend to occur where in the brain?
Grey/white matter junction (80%)
Vasogenic edema and mets?
usually out of proportion to the size of the mets
what is limbic encephalitis?
A paraneoplastic syndrome caused by non-CNS primary tumors resulting in functional and imaging changes in the limbic system. small cell carcinoma of the lung is the classic cause
The most common type of lymphoma to affect the brain is ?
diffuse histiocytic lymphoma
A feature highly suggestive of lymphoma?
Coating of the ventricles (seen in 38% of cases) and spread across the corpus callosum are features of lymphoma that are suggestive of, although
not specific for, the diagnosis of lymphoma.
an excellent means for distinguishing toxoplasmosis from CNS lymphoma.?
thallium scanning
Lymphoma is more commonly hyper or hypodense on CT? Does it enhance?
Hyperdense, enhances. May be hypodense occasionally in AIDS patients
ADC values high or low for lymphoma?
Lymphomas are said to have low ADC due to their dense
cellularity restricting water diffusion
The most common pineal tumor of the germ cell line is?
Germinoma
accounts for 60% of pineal germ cell tumors and 40%
of pineal region masses.
Sex distribution for germinoma near the pineal gland? Elsewhere?
This tumor, as in all germ cell tumors, has a distinct male predominance when seen in the pineal region (in some series as high as 33:1)
slight female predilection when seen suprasellarly.
what’s worse, pineoblastoma or pineocytoma?
We say germinomas “engulf” the pineal gland, and pineoblastomas “explode” the gland.
In patients with Lhermitte-Duclos disease, what disease is also found 50% of the time?
Cowden Syndrome - a multiple hamartoma syndrome.
LD is probably also a hamartomatous tumor of the cerebellum
AKA for Lhermitte-Duclos disease?
dysplastic gangliocytoma
