To report a rare case of a patient with diplopia due to a mass in the sphenoidal sinus, histologically diagnosed as carcinoma.

A 57-year-old male visited our clinic complaining of diplopia and ptosis for 10 days. He had esotropia 45 prism diopters in the primary position, markedly limited abduction, and a 4 mm dilated pupil in the right eye compared with a 2 mm pupil in the left eye. Enhanced magnetic resonance imaging revealed a sphenoidal sinus mass extended into the pituitary gland and sella turcica with homogeneous intense enhancement. Metastatic workups, including CT of the head, neck, chest, and abdomen were unremarkable. He underwent a transsphenoidal approach mass debulking surgery followed by radiotherapy for 6 weeks. Histological findings were compatible with carcinoma. Six weeks after radiotherapy he had esotropia of 20 prism diopters in the primary position. Abduction limitation was partially recovered postoperatively.

Diplopia may develop as a result of multiple cranial nerve palsy due to carcinoma in the sphenoidal sinus and may be improved by debulking surgery and radiation treatment.