Suprasellar Mass

Susan I. Blaser, MD, FRCPC

DIFFERENTIAL DIAGNOSIS

Common

Pilocytic Astrocytoma (PA)
Craniopharyngioma
Pituitary Hyperplasia (Physiologic)
Hydrocephalus

Less Common

Germinoma
Tuber Cinereum Hamartoma
Arachnoid Cyst
Langerhans Cell Histiocytosis
Pituitary Stalk Anomalies
Teratoma

Rare but Important

Lipoma
Pituitary Macroadenoma
Dermoid Cyst
Leukemia
Pilomyxoid Astrocytoma
Saccular Aneurysm
Retinoblastoma (Trilateral)
Lymphocytic Hypophysitis
Lymphoma, Primary CNS
Rathke Cleft Cyst

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Is mass extra- or intraaxial?
Extraaxial masses arise from pituitary/infundibulum, meninges, vessels
- If extraaxial mass appears to arise from pituitary/infundibulum, determine origin of mass as precisely as possible
  - Pituitary gland: Think physiologic hyperplasia, hypophysitis, macroadenoma (rare in children)
  - Infundibular stalk: Germinoma, histiocytosis; stalk anomalies, lymphoma, leukemia (rare)
- Nonpituitary extraaxial masses (normal pituitary gland can usually be identified inferior to lesion)
  - Craniopharyngioma
  - Hydrocephalus
  - Arachnoid cyst
  - Saccular aneurysm
Intraaxial masses arise from chiasm/hypothalamus/3rd ventricle
- Optic chiasm/hypothalamus: Pilocytic or pilomyxoid astrocytoma, tuber cinereum hamartoma, lipoma
- Third ventricle: Hydrocephalus > > neoplasm
T1 hyperintense suprasellar mass in child? Think craniopharyngioma, lipoma, dermoid, posterior pituitary ectopia

Helpful Clues for Common Diagnoses

Pilocytic Astrocytoma (PA)
- Most occur in children 5-15 years old
- Enlarged optic nerve/chiasm/tract
- Usually solid, iso-/hypointense on T1WI; hyperintense on T2WI, FLAIR
- Variable enhancement (none to intense)
- If large, bulky H-shaped mass in infant, may be pilomyxoid variant
Craniopharyngioma
- 90% Ca++ (globular, rim)
- 90% cystic (may have multiple)
- 90% enhance (rim, nodule)
- Density/signal intensity within cysts/locules varies with content
Pituitary Hyperplasia (Physiologic)
- Up to 10 mm height, convex superior margin in young menstruating females
- “Macroadenoma-appearing” mass in child?
  - May be hyperplasia, not tumor (especially prepubescent male)!
Hydrocephalus
- Enlarged 3rd ventricle (aqueductal stenosis, obstructive hydrocephalus)
- Anterior recesses protrude inferiorly
- May enlarge bony sella over time

Helpful Clues for Less Common Diagnoses

Germinoma
- 50-60% involve pituitary gland/stalk
- Often presents with diabetes insipidus (DI)
Tuber Cinereum Hamartoma
- Isosexual precocious puberty > gelastic seizures
- Pedunculated (“collar button”) or sessile mass between infundibular stalk, mamillary bodies
  - Can be tiny (1-2 mm) or giant (3-5 cm)
  - Isointense with gray matter (occasionally slightly hyperintense on FLAIR)
  - Doesn’t enhance
Arachnoid Cyst
- 10% suprasellar
- Sharply marginated CSF-like cyst
- Sagittal T1- or T2WI shows 3rd ventricle elevated, compressed over cyst
- Suppresses on FLAIR, DWI negative
Langerhans Cell Histiocytosis
- Child usually < 2 years old
  - May have central DI
- 10% of LCH cases involve stalk, pituitary gland ± hypothalamus
  - Rare: Choroid plexus, leptomeninges, cerebellar WM, brain parenchyma
- Look for solitary/multiple lytic skull lesions with “beveled edges”
Pituitary Stalk Anomalies
- Posterior pituitary ectopia
  - Short stature ± endocrine deficiencies
  - Posterior pituitary “bright spot” missing
  - Mislocated along tuber cinereum
  - Stalk small/absent
- Duplicated pituitary gland/stalk
  - Endocrinologically normal
  - ± midline facial anomalies
  - Tuber cinereum/mamillary bodies fused
Teratoma
- Optic chiasm > pineal
- Ca++, cysts, soft tissue, fat

Helpful Clues for Rare Diagnoses

Lipoma
- Fatty hypothalamic mass
Pituitary Macroadenoma
- “Figure of 8” pituitary mass
- Gland cannot be separated from mass
Dermoid Cyst
- Fat-like mass ± droplets in CSF
  - Fat suppression sequences confirm
- 20% Ca++
Leukemia
- Rare; look for other lesions (sinuses, dura)
Pilomyxoid Astrocytoma
- Rare variant of PA
- Large, bulky suprasellar mass in infant
- May hemorrhage (rare in PA)
Saccular Aneurysm
- Rare in children (< 2% of all saccular aneurysms occur in pediatric age group)
- When occur, often large/bizarre
- Thrombus common
- Look for residual patent lumen, phase artifact
Retinoblastoma (Trilateral)
- 3rd tumor in pineal or suprasellar region
Lymphocytic Hypophysitis
- Adolescent > child
- May cause DI
- Can mimic macroadenoma, pituitary apoplexy
Lymphoma, Primary CNS
- Rare in children
- Can mimic hypophysitis, germinoma, LCH
Rathke Cleft Cyst
- Rare in children
- Cyst in/above pituitary, separate from stalk
- Rarely calcifies, does not enhance (“claw” of enhancing pituitary tissue may surround mass)
- Intracystic nodule virtually pathognomonic

Image Gallery

Coronal T1 C+ MR shows chiasmatic glioma. The prechiasmatic optic nerves are expanded and surrounded by enhancing tumor.

Coronal T1WI C+ MR shows a very large suprasellar pilocytic astrocytoma. This solid and cystic mass involves the suprasellar cistern, the chiasm, the hypothalamus and protrudes into the 3rd ventricle.

(Left) Sagittal T1WI MR shows typical cysts of varying signal intensity in the suprasellar cistern, herniating into the 3rd ventricle. There is enlargement of the bony sella and erosion of the dorsum sella