Sellar Masses

Front 1

Macroadenomas

Back 1

Greater than 10 mm considered a macroadenoma.
25% non-secreting adenomas and usually macroadenomas.
Macroadenomas often manifest because of optic chiasm or nerve compression, hydrocephalus, cranial nerve palsies, or anterior pituitary dysfunction.
Isointense to gray matter on T1 and produce "draping" of the optic chiasm over top of the tumor.
Can be difficult to differentiate from craniopharyngiomas or parasellar meningiomas when heterogeous because of cyst formation or hemorrhage.

Front 2

Microadenoma

Back 2

Less than 10 mm
75% are hormonally active and most will be microadenomas.
Prolactinomas are most common- see amenorrhea, galactorrhea, or impotence. Level greater than 150 and greater than 1000 = invasion into the cavernous sinus.
On MR microadenomas best detected on T1 as focal areas of hypointensity compared to the rest of the gland. Contrast increases the conspicuity-revealed as hypointense foci within the gland on immediate post contrast scans or as hyperintense foci on deleyed imaging (30 min).

Front 3

Craniopharyngioma

Back 3

Arise from squamous epithelial remnants of the anterior lobe of the pituitary gland, derived from the pars tuberalis.
Frequently symptomatic because of their larger size: increased intracranial pressure, optic nerve or chiasm compression, or hypothalamic dysfunction.
Two peaks: between 5-10 and between 50-60.
Most involve both intrasellar and suprasellar compartments
Solid and cystic components are typical, with the fluid of the cysts often containing cholesterol crystals.
On CT, classic apperance is a large cystlike sellar/suprasellar mass with an enhancing rim and evidence of some calcifications.
On MR, because of the presence of the liquid cholesterol, the classic finding of hyperintensity on T1 and T2 corresponding to the cystic portion is common.

Front 4

Rathke's cleft cyst

Back 4

Arise from squamous epithelial remnants of the anterior lobe of the pituitary gland, from the pars intermedia
Often asymptomatic
Either purely intrasellar or intrasellar and suprasellar.
Rarely show peripheral enhancement.
Cyst contents are variable. Most commonly, a mucoid fluid fills the cysts. Because of variability may be hyperintense on T1 and T2 or may be isointense to hypointense b/c of cellular debri mimicking the appearance of a solid nodule.