T1 Isointense Suprasellar Mass

Anne G. Osborn, MD, FACR

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Where does lesion arise from?
- Pituitary gland/sella turcica (macroadenoma, hyperplasia, hypophysitis, metastasis)
- Infundibulum (germinoma, histiocytosis, pituicytoma)
- Brain (astrocytoma), meninges (meningioma)
Does it enhance?
- Yes: Macroadenoma, meningioma, aneurysm, neoplasm
- No: Tuber cinereum hamartoma, RCC
Few lesions remain isointense with cortex on all MR sequences
- Pituitary macroadenoma or hyperplasia
- Meningioma, tuber cinereum hamartoma
- Histiocytosis, sarcoidosis

Helpful Clues for Common Diagnoses

Pituitary Macroadenoma, Hyperplasia
- Both isointense to gray matter (GM)
Meningioma
- Usually isointense on all sequences
- ± Ca++, enhances
Astrocytomas (pilocytic > diffusely infiltrating)
- Usually iso-/hypo- on T1, hyperintense on T2WI
- Variable enhancement (none to striking)

Helpful Clues for Less Common Diagnoses

Rathke Cleft Cyst (depends on cyst content)
- Most are hypointense
- 25% iso-, 10% hyperdense
- Rim may enhance (“claw sign”)
Germinoma
- Isointense on T1-, iso/hypo on T2WI
- Enhances strongly, uniformly
Neurosarcoid, Langerhans Cell Histiocytosis
- LCH (child), sarcoid (adult) → thick, enhancing stalk
Tuber Cinereum Hamartoma
- > 90% isointense on T1WI, nonenhancing
- May be slightly hyperintense on PD, FLAIR