Files

T

Ross 9c86b32c3b .

2025-10-20 21:15:33 +01:00

35 KiB

Raw Blame History

title, docid, authors, breadcrumbs, category, cmeTopicId, documentVersionId, imageCount, lastUpdated, pageDescription, pageKeywords, pageTitle, enhancedTitle, type, references, breadcrumbs

title

docid

authors

breadcrumbs

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues
- Where does mass originate? - 3rd ventricle: Think hydrocephalus > intraventricular cystic mass (ependymal cyst, craniopharyngioma) - Suprasellar cistern: Arachnoid, other congenital/infectious cysts - Pituitary gland/sella turcica: Necrotic/cystic neoplasm or cyst - Brain parenchyma: Enlarged perivascular spaces, cystic/low density neoplasm - Hypothalamus/optic nerve: Cystic neoplasm
Helpful Clues for Common Diagnoses
- Enlarged 3rd Ventricle - CSF density/signal intensity - No enhancement (unless infection, neoplasm) - Obstructive hydrocephalus - Can be intra- or extraventricular (noncommunicating or communicating) - If acute, periventricular "halo" of transependymal CSF flow - "Cystic mass" = dilated 3rd ventricle - Aqueductal stenosis - ↑ lateral, 3rd ventricles - Normal 4th ventricle - Usually longstanding, "compensated" so no transependymal CSF
- Arachnoid Cyst - 10% of arachnoid cysts (ACs) suprasellar - Sharply marginated CSF density/signal intensity mass - Complete suppression on FLAIR - Does not restrict on DWI - 3rd ventricle elevated, displaced over AC - Displaces temporal lobes laterally - Displaces midbrain, pons posteriorly - Infundibular stalk typically displaced anteriorly - "Mickey mouse ears" on coronal = cyst + lateral ventricles - If large, may also cause obstructive hydrocephalus
- Craniopharyngioma - Adamantinomatous: 90% of childhood craniopharyngiomas cystic - Cyst fluid hyperdense/intense to CSF - 90% have some Ca⁺⁺ (globular or rim) - 90% enhance (rim, nodular) - Suprasellar cistern > > within 3rd ventricle
- Neurocysticercosis - Look for "clusters" of cysts in subarachnoid cisterns [racemose neurocysticercosis (NCC)] - Look for cyst + scolex - FLAIR best sequence to detect racemose NCC (cyst fluid does not suppress completely) - Scolex: T2 hypointense, DWI hyperintense
Helpful Clues for Less Common Diagnoses
- Rathke Cleft Cyst - 60% purely suprasellar or intrasellar with suprasellar extension - Variable density/signal intensity - Usually ↑ compared to CSF - Up to 10% calcify (curvilinear, in cyst wall) - No enhancement following contrast - Look for - Intracystic nodule (45-75%) - "Claw" of compressed, enhancing pituitary displaced around cyst
- Pituitary Macroadenoma - Solid ± intra- or extratumoral cysts common - Extratumoral cysts may be trapped/enlarged perivascular spaces or ACs - Cysts often hyperdense/intense compared to CSF - Solid > rim enhancement - Occasionally mostly cystic mass
- Dermoid Cyst - Most common site = sellar/parasellar, frontonasal - Fat density/signal intensity - 20% have capsular Ca⁺⁺ - Look for evidence of rupture - Fat droplets in subarachnoid spaces - Fat-fluid levels in ventricles - Chemical shift artifact in frequency encoding direction
- Epidermoid Cyst - Rare in suprasellar cistern - Lobulated, insinuating growth pattern - > 95% hypodense (similar to CSF) - FLAIR, DWI best to distinguish epidermoid from arachnoid cyst, enlarged 3rd ventricle - Epidermoid does not suppress completely on FLAIR, restricts on DWI
- Enlarged Perivascular Spaces - Usually variable-sized "clusters" - Off-midline (basal ganglia) - Round or ovoid (basal ganglia), linear (white matter) - Like CSF on all sequences (contain interstitial fluid) - Suppresses completely on FLAIR - Does not restrict on DWI
Helpful Clues for Rare Diagnoses
- Pituitary Apoplexy - Rare; may be life-threatening (severe panhypopituitarism) - Necrotic pituitary with little/no enhancement (may show rim) - Hemorrhage may bloom on T2* (GRE, SWI) - Compression/edema of hypothalamus, optic chiasm/tracts may cause hyperintensity on T2WI - May show DWI restriction, hypointense on ADC - Rarely associated with subarachnoid hemorrhage
- Astrocytoma - Pilocytic astrocytoma (PA) > > pilomyxoid astrocytoma - Pilocytic astrocytoma: WHO grade 1, occurs throughout neuraxis, including optic chiasm/hypothalamus - Often has cyst and mural nodule appearance - Pilomyxoid astrocytomaconsidered subtype of PA - Hypothalamic/chiasmatic most common location - Affects infants and young children; median 10 months - Most suprasellar astrocytomas are solid, T2 hyperintense, not grossly cystic - Variable enhancement
- Ependymal Cyst - Congenital, benign, ependymal-lined cyst - Lateral ventricle > > 3rd ventricle - Round/ovoid; CSF-like - Rare lesion
- Saccular Aneurysm - Aneurysms may be associated with true perianeurysmal cysts - Obstructed perivascular spaces posited as etiology - Partly or completely thrombosed may have cystic-appearing foci within clot - Rare - Acute thrombosis can present with panhypopituitarism, subarachnoid hemorrhage (SAH) - Imaging can mimic necrotic adenoma - Hypodense center, iso-/hyperintense rim on T1WI - Look for mixed-age laminated clot - Blooms on GRE, SWI - Rim may enhance
- Pituitary Abscess - Clinical signs of infection may be absent - May mimic pituitary apoplexy on MR - T1 shortening along rim and peripheral enhancement may be seen - DWI restriction characteristic
- Persistent Embryonic Infundibular Recess - Rare congenital malformation of neurohypophysis - Enlarged infundibular recess follows CSF - Communicates with anterior 3rd ventricle - May mimic cystic mass
Alternative Differential Approaches
- In childwith suprasellar cystic mass, consider enlarged 3rd ventricle (aqueductal stenosis, hydrocephalus), craniopharyngioma, NCC, astrocytoma
- In adult, consider AC, NCC, Rathke cleft cyst, adenoma, aneurysm

References

Selected References

Images

Selected Images

Aqueductal Stenosis Sagittal T2WI MR shows massively enlarged 3rd and lateral ventricles and an enlarged, funnel-shaped aqueduct related to aqueductal stenosis in this child. There is also a medial atrial diverticulum compressing the 4th ventricle .

Arachnoid Cyst Sagittal T2WI MR shows a cystic sellar and suprasellar mass related to an arachnoid cyst (AC). These benign lesions follow CSF on all MR sequences and do not enhance. The normal pituitary gland is usually thinned and wrapped anteriorly around the AC.

Craniopharyngioma Coronal T2 FS MR in a 7-year-old child with delayed growth shows a hyperintense suprasellar mass related to an adamantinomatous craniopharyngioma. These tumors are known as the 90% tumor, as 90% are cystic, calcified, and enhancing.

Craniopharyngioma Sagittal T1 C+ MR in a 32-year-old with headaches shows a mixed cystic and solid suprasellar mass. Although not seen in this case, papillary craniopharyngiomas often have more solid than cystic components. The papillary type is more common in adults.

Neurocysticercosis Axial T2 MR shows racemose (multilobulated, grape-like) neurocysticercosis (NCC) cysts extending into the suprasellar cistern and the cerebellopontine angles . Racemose NCC typically involves the basal cisterns and lacks an identifiable scolex.

Rathke Cleft Cyst Coronal T2 MR shows a sellar/suprasellar cyst in a 29-year-old woman with mild prolactin elevation. Rathke cleft cysts may present with symptoms related to mass effect. The prolactin elevation in this case was related to stalk effect from the cyst compressing the stalk.

Pituitary Macroadenoma Coronal T1 C+ MR shows a cystic macroadenoma with mild mass effect on the left optic chiasm . Imaging in this young adult female with amenorrhea and markedly elevated prolactin mimics a Rathke cleft cyst.

Dermoid Cyst Sagittal T1 MR shows a large midline mass with intrinsic T1 shortening within the subfrontal region above the optic chiasm along the 3rd ventricular floor . T1-hyperintense "droplets" are seen scattered throughout the subarachnoid space related to a ruptured dermoid.

Epidermoid Cyst Axial DWI MR shows an epidermoid cyst in the left suprasellar cistern . These benign cysts classically show restricted diffusion as seen in this example. They are often T2 hyperintense and lack suppression on FLAIR sequences. Surgical resection is the treatment of choice.

Enlarged Perivascular Spaces Sagittal T1WI MR in a 15-year-old with headaches shows multiple CSF-like cysts in the hypothalamus, thalamus, and midbrain that bulge into the suprasellar subarachnoid space .

Pituitary Apoplexy Axial T2 MR shows a large pituitary macroadenoma with cavernous sinus invasion on the right. There is a blood fluid level related to hemorrhage in this patient who presented with acute headache, visual changes, and ophthalmoplegia. Pituitary apoplexy may be caused by hemorrhage or infarction of the pituitary gland, often within an adenoma.

Pilomyxoid Astrocytoma Sagittal T2WI MR shows a very hyperintense suprasellar mass, almost as bright as CSF. A thin rim of normal-looking brain borders the mass , indicating its intraaxial origin.

Saccular Aneurysm Axial T1WI MR shows a partially thrombosed saccular aneurysm . Part of the clot is very hypointense and is seen here as a mass in the suprasellar cistern.

Pituitary Abscess Coronal DWI MR shows diffusion restriction in the pituitary fossa in this 71-year-old woman with a sellar abscess. The patient presented with altered mental status and meningitis. Additional focus of DWI hyperintensity is related to the patient's meningitis. Diffuse meningeal enhancement was seen on postcontrast images (not shown).

Additional Images

Enlarged 3rd Ventricle Sagittal T2WI MR shows obstructive hydrocephalus with markedly enlarged lateral and 3rd ventricles. The CSF suprasellar mass was related to an enlarged 3rd ventricle from a pineal region germinoma . Germinomas most commonly present in the pineal region.

Obstructive Hydrocephalus Sagittal T2WI MR shows extraventricular obstructive hydrocephalus (EVOH) with markedly enlarged lateral , 3rd , and 4th ventricles. A CSF suprasellar mass caused by an enlarged 3rd ventricle was diagnosed.

Arachnoid Cyst Coronal T1 C+ MR shows a large CSF-like cyst that elevates and compresses the 3rd ventricle and causes obstructive hydrocephalus. Note straight cyst margins .

Arachnoid Cyst Sagittal T2WI FS MR shows a lobulated, sharply marginated, CSF-like, suprasellar cyst extending into the sella , elevating the 3rd ventricle , and causing obstructive hydrocephalus.

Arachnoid Cyst Coronal T2WI MR shows a small AC in the suprasellar cistern that elevates and compresses the optic chiasm. Note both intra- and suprasellar components of the cyst.

Craniopharyngioma Coronal T2WI FS MR in an 8-year-old child with delayed growth shows a hyperintense suprasellar mass that slightly compresses and displaces the pituitary gland toward the left.

Craniopharyngioma Sagittal gross pathology, section shows a classic craniopharyngioma with a large suprasellar cystic component . Smaller intrasellar component is present . (Courtesy R. Hewlett, MD.)

Craniopharyngioma Sagittal T2WI MR in a 32-year-old with headaches and lethargy shows a hyperintense mixed cystic and solid suprasellar mass that extends superiorly into the 3rd ventricle and results in mass effect on the midbrain. This was pathologically proven to represent a papillary craniopharyngioma. Although not seen in this case, papillary craniopharyngiomas tend to have more solid than cystic components. The papillary subtype is more commonly seen in the adult population and is overall less common than the adamantinomatous subtype.

Rathke Cleft Cyst Sagittal T1 C+ MR shows an intra- and suprasellar cyst that does not enhance. Note the displaced pituitary gland and infundibular stalk form a "claw" around the lesion.

Neurocysticercosis Coronal T2WI MR shows a suprasellar cystic mass and a moderate compensated hydrocephalus. Another cyst is present in the right Meckel cave in this patient with racemose NCC.

Neurocysticercosis Coronal T1 C+ MR shows racemose neurocysticercosis with multiple cysts in the suprasellar cistern and 3rd ventricle . Enhancement in the right sylvian fissure is present.

Enlarged Perivascular Spaces Axial NECT shows multiple clusters of CSF-like cysts . These are actually in brain parenchyma, helping distinguish them from other suprasellar cystic lesions.

Epidermoid Cyst Coronal T2WI MR shows an epidermoid cyst in the left suprasellar cistern with mass effect on the optic chiasm superiorly and the pituitary gland inferiorly. These benign cysts classically show restricted diffusion and lack suppression on FLAIR sequences. Surgical resection is the treatment of choice.

Epidermoid Cyst Axial T2WI MR shows an epidermoid cyst in the suprasellar cistern, widening the interpeduncular fossa and extending into the ambient and quadrigeminal cisterns.

Epidermoid Cyst Coronal T2WI MR shows an epidermoid cyst in the suprasellar cistern with a lobulated appearance and associated ventriculomegaly. These benign cysts classically show restricted diffusion and lack suppression on FLAIR sequences. Surgical resection is the treatment of choice.

Pituitary Macroadenoma Coronal T2 MR shows a cystic macroadenoma with mild mass effect on the left optic chiasm in a 41-year-old with elevated growth hormone.

Pituitary Macroadenoma Axial T1 C+ MR shows 2 neoplasm-associated cysts: A large trapped perivascular space caused by a pituitary macroadenoma and a small intratumoral cyst within the adenoma.

Pituitary Apoplexy Axial CECT shows pituitary apoplexy caused by a necrotic pituitary macroadenoma . Imaging appearance resembles a thrombosed aneurysm.

Dermoid Cyst Axial NECT shows a large, mixed density suprasellar and subfrontal mass . Low density "droplets" that resemble fat are seen in the adjacent sylvian fissure in this patient with a ruptured dermoid. Ca⁺⁺ may be seen in up to 20% of dermoid cysts.

Ependymal Cyst Sagittal STIR MR with a close-up view shows a large cystic lesion within the 3rd ventricle . The lateral ventricles are markedly enlarged, but the 4th ventricle is normal.

35 KiB Raw Blame History

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Helpful Clues for Common Diagnoses

Helpful Clues for Less Common Diagnoses

Helpful Clues for Rare Diagnoses

Alternative Differential Approaches