Features are in keeping with Rathke's cleft cyst rather than craniopharyngioma. It is well known that Rathke cleft cysts have variable signal intensities. The most reported is the T2 hypointense signal, which is highly suggestive 1. T2 hyperintensity is also described in about 70% of cases. The difference in signal between the upper and lower parts is called the "stratification effect" 2. Rathke cleft cysts have different signal appearances in each pulse sequence depending on its content chemical nature 3.
Craniopharyngioma is the main differential diagnosis at this age. It tends to be suprasellar rather than sellar, parenchyma tissue is always present despite significant cystic changes, and the presence of calcifications. Also, signal intensities in this case are indistinguishable from pituitary apoplexy 4.