Cysts
- Colloid
cyst
- 20-40
years, M=F
- Pedunculated
round cyst arising in the anterior 3rd ventricle
- anterior
roof of third ventricle between fornices
- attached
to stroma of choroid
- endodermal
origin – from vestigial structure (paraphysis)
- hyper
T1, hypo T2, cyst wall enhances
- filled
with mucopolysaccharides
- no
calficiation
- Symptoms:
intermittent HAs, obstructive hydrocephalus, short-term memory loss if large
- Can present
with headaches or drop attacks
- There
are reported cases of sudden death secondary to acute obstruction of
ventricular outflow and herniation from resulting hydrocephalus
- Diagnosis:
Head CT shows high density round lesion within the 3rd ventricle
- Treatment:
Surgical excision
- Arachnoid
cyst
- M>F;
only 30% symptomatic
- Middle
fossa most common location (also suprasellar, quadrigeminal, posterior
fossa, convexity)
- Can
cause SDH (tearing of vein)
- Symptoms:
Usually an incidental finding when patient is imaged for some other
reason
- Occasionally
cause mass effect and lead to increased ICP and focal neurologic deficit
- Diagnosis:
Well demarcated low density (equivalent to CSF) cystic lesion without
enhancement
- Location:
Middle fossa, convexity, suprasellar, posterior fossa
- Treatment:
If symptomatic – surgical fenestration or shunting
- Asymptomatic
– no treatment
- Rathke’s
cleft cyst
– remnant of craniopharyngeal duct
- F>M,
30-40 years
- 70%
supra and infrasellar
- 50%
enhance
- symptoms
usually visual change or increased prolactin (stalk effect)
- no
calcification
- watery
mucous fluid with ciliated columnar cells with goblet cells
- Epidermoid – 1% intracranial tumors;
usually off midline
- 30-50
years old, M=F
- CPA most
common location (also suprasellar, intraventricular, thalamic, pons,
cerebellar cistern)
- 10%
extradural or intradiploic
- 50%
calcify
- Result
from the inclusion of ectodermal rests during the closure of the neural
tube
- Enlarges
slowly as the stratified squamous epithelium continues to desquamate its
surface cells
- Radiology:
Lobulated cystic lesion with density lower than CSF and no enhancement
- Treatment:
Surgical excision
- Rupture
of cyst contents into CSF can result in a severe chemical meningitis (Mollaret’s)–
treat with high dose steroids
- Dermoid – 0.1% of intracranial tumors;
most common parasellar (also fourth ventricle, hemispheric, spinal);
midline
- Result
from the inclusion of both mesodermal and ectodermal elements during
gestation
- Peak
incidence is in the 1st three decades with a slight female
predominance
- Location
tends to be midline (posterior fossa near the 4th ventricle,
parasellar, pineal, ventricular, intraparenchymal)
- Radiology: Well defined mass with areas
of marked hypodensity consistent with fat
- Rx: surgical excision
- Prognosis: Many long-term survivors
- Neuroepithelial
cyst
- Infolding
of developing neuroectoderm
- Ependymal,
choroid plexus
- Neuroenteric
cyst (enterogenous cyst)
- Single
layer of cuboidal/columnar cells with goblet cells
- GI or
respiratory mucosa
- Usually
spine or CPA