A 79-year-old man was referred with acute left upper eyelid droop and binocular diplopia without headache, nausea, or changes in visual acuity.

The patient had a history of pituitary adenoma resection 16 years before and recent bladder carcinoma treated with immunotherapy.

Visual acuity was 20/30 in the right eye and 20/25 in the left eye. There was a pronounced left upper eyelid ptosis with margin reflex distance of 1 mm and decreased levator function. Extraocular motility was notable for a slight limitation in upward duction of the left eye. There was no hypoesthesia or anesthesia of the face.

There was strong suspicion of a left-side partial third-nerve palsy. An urgent MRI was obtained and showed a sellar and suprasellar mass, measuring 2.0 × 3.5 × 2.0 cm. The mass invaded bilateral cavernous sinuses without mass effect on the optic chiasm (Fig. A, B). The mass appeared to contact and partially encase the bilateral cavernous internal carotid arteries, as well as the basilar artery and bilateral posterior cerebral arteries.

Surgical excision confirmed a mucocele extending from the sphenoid sinus.

Pituitary apoplexy has previously been reported as a cause of third-nerve palsy; however, mucoceles as a cause are poorly represented in the literature to date. While oculomotor nerve deficit is a rare known complication of transsphenoidal surgery for pituitary adenomas, patients with new-onset diplopia and ptosis even many years after their initial resection should be carefully evaluated with imaging for recurrence or new masses when clinical findings warrant. Clinicians should also be mindful that late-onset problems after surgery can develop.