The imaging appearances of this case are highly suspicious for an adamantinomatous craniopharyngioma. Differentials for similar masses in this location, much less likely in this case,

• Rathke cleft cyst
  • no solid or enhancing component
  • calcification is rare
  • unilocular
  • the majority are completely or mostly intrasellar 
• pituitary macroadenoma (with cystic degeneration or necrosis)
  • can look very similar
  • usually has intrasellar epicenter with pituitary fossa enlargement rather than the suprasellar epicenter
  • despite occasional presence of T1 bright cystic regions, calcification in these cases is often absent (whereas most adamantinomatous craniopharyngiomas are calcified)
• intracranial teratoma
  • presence of fat is helpful but requires fat saturated sequences or CT to confirm

MICROSCOPIC DESCRIPTION: Paraffin sections show several fragments of an adamantinomatous craniopharyngioma. These consist of irregularly shaped islands of epithelium with prominent peripheral basaloid cell layers, central squamous epithelium with focal keratinization and intermediate stellate reticulum. No mitotic figures or areas of necrosis are identified. Adjacent brain parenchyma shows well-developed piloid gliosis with numerous Rosenthal fibers identified.

DIAGNOSIS:  Sellar region lesion: adamantinomatous craniopharyngioma.