A 45-year-old man presents with progressive bitemporal hemianopia. MRI reveals a mass compressing the optic chiasm from below. Which structure is most likely responsible?
- A Meningioma of the tuberculum sellae
- B Craniopharyngioma
- C Pituitary adenoma ✓
- D Internal carotid artery aneurysm
Correct answer: C. Pituitary adenoma
Explanation
Bitemporal hemianopia results from compression of crossing nasal retinal fibers at the optic chiasm. Pituitary adenoma is the most common lesion causing chiasmal compression from below. Craniopharyngioma and tuberculum sellae meningioma also compress the chiasm but are less common. Internal carotid aneurysm is a rare cause. The key discriminating fact is that pituitary adenoma accounts for the majority of chiasmal syndromes in adults.
Reference: Williams Textbook of Endocrinology, 14th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.