Although the appearances are most consistent with a pituitary macroadenoma, given the high T2 signal the possibility of this mass representing a chordoma was entertained.

The patient went on to have a resection. 

Histology

Microscopic Description: 

Sections show multiple pieces of pituitary adenoma, associated with nasopharyngeal mucosa, and thin portions of bone. Extremely sparse cells are immunoreactive for ACTH. There is negative immunoreactivity for growth hormone, prolactin, FSH, TSH and LH.

Final diagnosis: Pituitary adenoma, null cell type.