Table 2.

Differential diagnosis table for sellar/suprasellar mass.

Differential diagnosis	Typical location	CT	MRI	18F-FDG PET
Intracranial chordoma	Clivus	Hyperdense enhancing mass with internal calcifications due to adjacent bone erosion.	Enhancing mass that shows mild T1w hypointensity or isointensity with T2w hyperintensity. Calcifications will appear as signal voids or blooming artefact on T2*w sequence.	Hypermetabolic.
Pituitary macroadenoma	Sella	Slightly hyperdense enhancing mass. May be more hyperdense if complicated by apoplexy or hypodense if there is cystic degeneration. Sella turcica may be scalloped. Invasive subtype of pituitary adenomas can erode the bone.	Enhancing mass that shows isointense T1w/T2w signals to gray matter. May be T1w hyperintense if complicated by apoplexy or T1w hypointense/T2w hyperintense if there is cystic degeneration.	Hypermetabolic unless there is cystic degeneration where the cystic area will be hypometabolic.
Perisellar aneurysm	Arising from supraclinoid or cavernous internal carotid arteries	Hyperdense mass with rim calcification and contrast opacification similar to blood pool.	Mass with rim T1w/T2w hypointensity and contrast opacification similar to blood pool.	Similar to blood pool.
Meningioma	Sphenoid wings	Isodense to slightly hyperdense mass with avid contrast enhancement, dural tail and adjacent bone hyperostosis. A third calcifies.	Enhancing mass that shows isointense T1w/T2w signals to gray matter. Avid contrast enhancement, dural tail and adjacent bone hyperostosis.	Hypermetabolic with more avid radiotracer uptake in higher grade tumors.
Plasmacytoma	Aerodigestive tract, head and neck region	Enhancing soft tissue mass with punched-out lytic bone destruction. In advanced disease and solitary bone plasmacytoma, there is also expansion of the affected bones. May have lymphadenopathy.	Enhancing mass with punched-out lytic bone destruction. In advanced disease and solitary bone plasmacytoma, there is also expansion of the affected bones. May have lymphadenopathy.	Hypermetabolic.
Chondrosarcoma	Petro-occipital fissures	Heterogeneously enhancing mass with expansion, bony destruction and endosteal scalloping. Characteristic ring and arc calcifications denote chondroid matrix.	Heterogeneously enhancing mass with mild T1w hypointensity to gray matter and T2w hyperintensity. Calcifications will show susceptibility artefact on T2*w sequence. May show higher ADC value compared to chordoma.	Hypermetabolic with more avid radiotracer uptake in higher grade tumors.
Ecchordosis physalifora	Retroclival, prepontine cistern	Not best modality due to streak artefact in posterior fossa.	Non-enhancing intradural mass with T1w hypointensity and T2w hyperintensity. Stalk attached to clivus.	No literature is available but possibly hypometabolic.