Prolactinomas

A 42-year-old man presents with decreased libido, erectile dysfunction, and headaches. He reports no weight change, gynecomastia, fatigue, or other symptoms. He takes no medications. Testicular size is decreased. His prolactin level is 648 μg per liter (normal value, <15). Magnetic resonance imaging reveals a sellar mass (2.5 by 1.5 by 2.0 cm) that is 5 mm below the optic chiasm and that extends bilaterally into the cavernous sinuses. What are the diagnostic and therapeutic considerations?