A case report of pituitary neuroendocrine tumor manifesting as severe conjunctival chemosis.

BACKGROUND: Conjunctival chemosis (CC) is an extremely rare symptom of pituitary neuroendocrine tumor (PitNET). We report an extremely rare case of PitNET manifesting as severe CC. CASE PRESENTATION: A 48-year-old male was admitted to our hospital with severe CC, proptosis, and ptosis of the right eye. Magnetic resonance imaging demonstrated the tumor mass invading the cavernous sinus (CS) with cystic lesion. The patient underwent emergent endoscopic transsphenoidal surgery, and the pathological diagnosis was PitNET. CC of the right eye remarkably improved after the surgery. Glucocorticoid therapy was performed for right oculomotor nerve palsy, which rapidly improved. The postoperative course was uneventful and the patient was discharged from our hospital without hormone replacement. CONCLUSIONS: CC caused by CS invasion of PitNET can be cured by early surgical treatment. Therefore, PitNET is important to consider in the differential diagnosis of CC.