Intrasellar Lesion
Anne G. Osborn, MD, FACR
DIFFERENTIAL DIAGNOSIS
Common
Pituitary Hyperplasia
Pituitary Microadenoma
Empty Sella
Less Common
Pituitary Macroadenoma
Rathke Cleft Cyst
Craniopharyngioma
Neurosarcoid
Rare but Important
Lymphocytic Hypophysitis
Intracranial Hypotension
“Kissing Carotid Arteries”
Saccular Aneurysm
Meningioma
Metastasis to Gland/Stalk
Lymphoma, Primary CNS
Dural A-V Fistula
CNS Siderosis
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Not all “enlarged pituitary glands” are abnormal!
Size/height varies with gender, age
Pituitary “incidentaloma” (cyst, nonfunctioning adenoma) in 15-20% of normal MRs
If it doesn’t enhance, cyst is a more likely etiology than microadenoma
Helpful Clues for Common Diagnoses
Pituitary Hyperplasia
Physiologic (e.g., young menstruating or postpartum females)
Pathologic (end-organ failure, neuroendocrine tumors, etc.)
Pituitary Microadenoma
< 10 mm in diameter, may enlarge gland
70-90% hypointense, enhance more slowly than normal pituitary
Empty Sella
Intrasellar CSF collection → pituitary gland flattened against sellar floor
5-10% prevalence on MR
Helpful Clues for Less Common Diagnoses
Rathke Cleft Cyst
T1WI: 50% hypo-, 50% hyperintense
T2WI: 70% hyper-, 30% iso-/hypointense
Look for “intracystic nodule” (45-50%)
Craniopharyngioma
Completely intrasellar craniopharyngioma uncommon
Helpful Clues for Rare Diagnoses
Lymphoma, metastasis often infiltrate adjacent structures
Venous engorgement → bulging gland
Look for intracranial hypotension, dAVF
CNS Siderosis
“Black” pituitary gland on T2*
Found with iron overload states > > SAH
Thalassemia
Hemochromatosis
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