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.