Suprasellar Cystic Mass

Suprasellar Cystic Mass

Anne G. Osborn, MD, FACR



  • Enlarged Third Ventricle

    • Obstructive Hydrocephalus

    • Aqueductal Stenosis

  • Arachnoid Cyst

  • Craniopharyngioma

  • Neurocysticercosis (NCC)

Less Common

  • Rathke Cleft Cyst

  • Dermoid Cyst

  • Epidermoid Cyst

  • Enlarged Perivascular Spaces (PVSs)

Rare but Important

  • Pituitary Macroadenoma

  • Pituitary Apoplexy

  • Astrocytoma

    • Pilocytic Astrocytoma

    • Pilomyxoid Astrocytoma

  • Ependymal Cyst

  • Saccular Aneurysm


Key Differential Diagnosis Issues

  • Where does the mass originate?

    • Third ventricle: Think hydrocephalus > intraventricular cystic mass (ependymal cyst, craniopharyngioma)

    • Suprasellar cistern: Arachnoid, other congenital/infectious cysts

    • Pituitary gland/sella turcica: Necrotic/cystic neoplasm

    • Brain parenchyma: Enlarged perivascular spaces, cystic/low density neoplasm

Helpful Clues for Common Diagnoses

  • Enlarged Third Ventricle

    • CSF density/signal intensity

    • No enhancement (unless infection, neoplasm)

    • Obstructive Hydrocephalus

      • Can be intra- or extra-ventricular (noncommunicating or communicating)

      • If acute, periventricular “halo” of transependymal CSF

      • “Cystic mass” = dilated 3rd ventricle

    • Aqueductal Stenosis

      • ↑ Lateral, 3rd ventricles

      • Normal 4th ventricle

      • Usually longstanding, “compensated” so no transependymal CSF

  • Arachnoid Cyst

    • 10% of ACs suprasellar (SSAC)

    • Sharply marginated CSF density/signal intensity mass

      • Suppresses 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

    • 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 (NCC)

    • Look for “clusters” of cysts in subarachnoid cisterns (“racemose” NCC)

    • Look for cyst + scolex

    • FLAIR best sequence to detect (cyst fluid doesn’t suppress completely)

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

      • 10% calcify (curvilinear, in cyst wall)

    • Look for

      • Intracystic nodule (45%)

      • “Claw” of compressed, enhancing pituitary displaced around cyst

  • 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 AC, enlarged 3rd ventricle

      • Epidermoid doesn’t suppress completely, restricts on DWI

  • Enlarged Perivascular Spaces (PVSs)

    • 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 Macroadenoma

    • Solid ± intra- or extratumoral cysts

      • Extratumoral cysts may be trapped/enlarged PVSs or arachnoid cysts

      • Cysts often hyperdense/intense compared to CSF

    • Solid > rim enhancement

  • 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

    • Restricts on DWI

    • Markedly hypointense on ADC

  • Astrocytoma

    • Pilocytic > > pilomyxoid astrocytoma

    • Most suprasellar astrocytomas are solid, not grossly cystic

  • Ependymal Cyst

    • Rare; 3rd ventricle least common site

    • Round/ovoid; CSF-like

  • 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, SAH

    • Imaging can mimic necrotic adenoma

      • Hypodense center, iso-/hyperintense rim on T1WI

      • Look for mixed age laminated clot

      • “Blooms” on GRE

      • Rim may enhance

Image Gallery

Sagittal T2WI MR shows EVOH with markedly enlarged lateral image, 3rd image, and 4th image ventricles. A CSF suprasellar mass caused by an enlarged 3rd ventricle was diagnosed.

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Aug 7, 2016 | Posted by in NEUROLOGY | Comments Off on Suprasellar Cystic Mass

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