extra axial masses Flashcards
What is the presumed reasoning for increased incidence of meningioma in middle aged women?
increased sensitivity of tumoral arachnoid cap cells to sex hormones
Where are the common locations for meningioma?
Parasagittal/falcine - 50% Sphenoid wing 20% Anterior cranial fossa - 10% Parasellar 10% Tentorium and CPA
Can meningioma erode bone?
YES
What are the two main DDX for meningioma?
Mets
Sarcoid
What is the MR spec appearance of meningioma?
peak at 1.5ppm corresponding to alanine
What makes up epidermoid cysts? Dermoid?
Intracranial inclusion of epithelial elements during neural tube closure
Intracrainal inclusion of ectodermal elements during neural tube closure
Where are epidermoids usually found?
CPA - 50%
Sella and parasellar 10-15%
4th ventricle and prepontine cistern
When an epidermoid is found in children in the posterior fossa, what should be considered?
Klippel fleil syndrome and the possibility of infection
Where do dermoids occur usually?
Lumbar spine Parasellar region Floor of anterior cranial fossa Post fossa including 4th ventricle Fontanelles
What is the imaging appearance of dermoid? What is the risk with rupture?
Matches fat on all sequences
Chemical meningitis due to leakage of contents into CSF space
Where do lipoma occur in the head?
80% midline
What is the appearance of pericallosal lipoma?
Calcification
Curvilinear with a normal appearing corpus callosum
What age group get choroid plexus tumors?
85% are
Where do choroid plexus papilloma occur in kids vs adults
Kids - atrium of lateral ventricle
Adults - 4th ventricle
Who gets choroid plexus carcinoma? When are they suspected?
Kids only
Surrounding edema and invasion of the parenchyma
What is the main differential for choroid plexus tumor?
Ependymoma, meningioma, mets, astrocytoma
When should one suspect a choroid plexus tumor?
Solid vascular tumors in the 4th vent (adults) and lateral ventricle (kids) with vivid frond like enhancement and speckled calcification
What percentage are active? With which hormone most commonly?
75-80%, prolactin
What serum levels of prolactin will have a visible mass in MR? What level suggests cavernous sinus invasion?
200
1000
What are the two types of craniopharyngioma?
Adamantinomatous (cystic, in kids)
Papillary (solid, adults)
What is the imaging of a craniopharyngioma?
Calcifying enhancing cystic lesion in the sella midline
What is the classification of pineal tumors?
By germ cell
What is the most common type of pineal tumor?
Germinoma
hyperdense CT
low ADC/T2/FLAIR, avidly enhance
What is the age group for pinealblastoma?
What is the MRS of pinealblastoma?
No neurons, so no NAA
Where do colloid cysts usually arise?
anterosuperior third ventricle
What are the symptoms of colloid cyst?
Positional headache due to moving colloid ball that obstructs the foramen of munro
What is the imaging of colloid cyst?
Low t1 high T2 due to proteinaceous material
Fried egg appearance with nodule of high or low signal intensity
Where is the most common site for arachnoid cyst?
Middle cranial fossa and sylvian fissure
What are the secondary signs of arachnoid cyst?
Scalloping adjacent bone change
Balloon valve mechanism
Production of CSF
What conditions are associated with multiple arachnoid cysts?
Glutaric acidura
Tuberous sclerosis
MPS
