A large lobulated cystic appearing mass is seen with both intra and suprasellar components. The suprasellar component compresses the prechiasmal right optic nerve and hypothalamus. The infundibulum is compressed and deviated to the right. The sella is remodelled. Pituitary tissue appears compressed on the floor and posteriorly in the sella. Thin linear septal enhancement is evident internally. No restricted diffusion, susceptibility artefact, intrinsic T1 hyperintensity or solid enhancement.
Conclusion:
A Rathke's cleft cyst, or possibly an arachnoid cyst, is favoured. Less likely differential diagnoses include cystic macroadenoma and craniopharyngioma.