Granulomatous hypophysitis is a rare pituitary condition that commonly presents with enlargement of the pituitary gland. A 31-year-old woman was admitted to the hospital with a severe headache and bitemporal hemianopsia. Magnetic resonance imaging (MRI) showed an 18 × 10-mm sellar mass with suprasellar extension and compression of the optic chiasm. Interestingly, brain MRI had shown no abnormal finding 4 months previously. On hormonal examination, hypopituitarism with mild hyperprolactinemia was noted. The biopsy revealed granulomatous changes with multinucleated giant cells. We herein report this rare case and discuss the relevant literature.