Third Ventricle Mass, General
Karen L. Salzman, MD
DIFFERENTIAL DIAGNOSIS
Common
MR Artifacts, Flow-Related
Massa Intermedia, Normal
Colloid Cyst
Less Common
Germinoma
Neurocysticercosis
Neurosarcoid
Prominent Massa Intermedia, Chiari 2
Vertebrobasilar Dolichoectasia (Mimic)
Rare but Important
Choroid Plexus Papilloma
Craniopharyngioma
Pituitary Macroadenoma
Tuber Cinereum Hamartoma
Chordoid Glioma
Lymphoma, Primary CNS
Langerhans Cell Histiocytosis
Glioma
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Vast majority of 3rd ventricular “masses” are artifact or normal anatomy
Colloid cyst is only common lesion that is classically located in 3rd ventricle
These masses often occur in other locations but may occur primarily in 3rd ventricle
Germinoma, choroid plexus papilloma, craniopharyngioma, macroadenoma, lymphoma, hypothalamic hamartoma
Newly described rare tumor, chordoid glioma is primary to 3rd ventricle
Helpful Clues for Common Diagnoses
MR Artifacts, Flow-Related
May be differentiated from true mass by associated phase artifact
Multiplanar technique confirms artifact
Massa Intermedia, Normal
Normal grey matter connection of medial thalamus (interthalamic adhesion)
Absent in up to 20% of human brains
Unclear function
Colloid Cyst
99% wedged into foramen of Monro
Attached to anterior 3rd ventricular roof
Pillars of fornix straddle, drape around cyst
Posterior part of frontal horns splayed laterally around cyst
Helpful Clues for Less Common Diagnoses
Germinoma
CNS germinomas have a propensity to hug the midline near 3rd ventricle ˜ 80-90%
Location: Pineal region ˜ 50-65%; suprasellar ˜ 25-35%; basal ganglia and thalami ˜ 5-10%
Primary intraventricular germinoma involving 3rd ventricle is rare
Ventricles usually involved from CSF dissemination
Neurocysticercosis
Convexity subarachnoid spaces most common location
May involve cisterns > parenchyma > ventricles
Intraventricular cysts are often isolated, 4th ventricle most common
Neurosarcoid
Solitary or multifocal CNS mass(es) with lung disease
Location: Dura, leptomeninges, subarachnoid space most common
Often involves basal cisterns, particularly optic chiasm, hypothalamus, infundibulum, cranial nerves
Brain parenchyma: Hypothalamus > brain stem > cerebral > cerebellar hemispheres
Ventricular system variably involved, commonly associated with hydrocephalus
Prominent Massa Intermedia, Chiari 2
Large massa intermedia, typical of Chiari 2
Third ventricle may be high-riding if corpus callosum agenesis present
Vertebrobasilar Dolichoectasia (Mimic)
Long segment irregular fusiform or ovoid arterial dilatation
Typically occurs in vertebrobasilar system more than carotid circulation
Ectatic basilar artery may indent 3rd ventricle and/or foramen of Monro
MR (flow artifact) or CTA is diagnostic
Helpful Clues for Rare Diagnoses
Choroid Plexus Papilloma
Strongly enhancing, lobulated, intraventricular mass in child
Location: Atrium of lateral ventricle (50%), left > right; 4th ventricle (40%)
3rd ventricle primary less than 10%
Craniopharyngioma
Partially cystic/solid, calcified suprasellar mass in child
Location: Suprasellar (75%); suprasellar and intrasellar (21%); intrasellar (4%)
Rare ectopic locations: 3rd ventricle, nasopharynx, sphenoid sinus
Pituitary Macroadenoma
Enhancing sellar and suprasellar mass
Rarely have ectopic origins outside pituitary fossa
3rd ventricle, sphenoid or cavernous sinus, pituitary stalk
Tuber Cinereum Hamartoma
Nonneoplastic congenital collection of heterotopic neurons and glia originating from tuber cinereum (3rd ventricle floor)
Small (typically ˜ 1 cm), round, mass contiguous with tuber cinereum
Sessile or pedunculated round mass, similar in density/intensity to gray matter
T1 C+: Nonenhancing (if enhances, consider glioma or other tumor)Related posts:
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