A 53-year-old White gentleman, with no significant past medical history other than active tobacco use, woke up with a sudden onset of double vision and severe frontal headaches (Fig 1). In the past 4 weeks, his vision progressively worsened and he developed left facial numbness. Because of deterioration of his symptoms, the patient was seen by ophthalmology and found to have a left lateral gaze. His magnetic resonance imaging showed a 34 mm × 17 mm clival mass with extension into the prepontine cistern, both Meckel’s caves, both sphenoid sinuses, and both petrous apices (Fig 3, Row 1). Additionally, the mass showed encasement of the left cavernous internal carotid artery. The combination of worsening vision and mass location led to the differential diagnosis of macroadenoma, neural primary malignancy, or metastatic carcinoma of unknown primary.