Endoscopic endonasal surgery for suprasellar ectopic pituitary neuroendocrine tumors featuring apoplexy and a preoperative differential diagnosis: illustrative cases.

backgroundEctopic pituitary neuroendocrine tumors (Pit-NETs) are rare. The authors present two cases of ectopic Pit-NETs located entirely in the suprasellar space without continuity with the normal pituitary gland. OBSERVATIONS: In case 1, a 53-year-old male presented with right blindness and left visual field impairment. Preoperative imaging suggested an ectopic Pit-NET with pituitary apoplexy. Intraoperatively, it was found to originate from the pars tuberalis of the pituitary stalk. A portion of the tumor inside the pituitary stalk was left intact, resulting in subtotal resection. Postoperatively, the patient developed diabetes insipidus (DI), but his left visual function improved. In case 2, a suprasellar tumor was incidentally discovered in a 63-year-old female who presented with a headache. Imaging revealed a tumor with a cystic component, leading to an initial diagnosis of craniopharyngioma. Intraoperatively, the tumor was found to originate from the pituitary stalk. The stalk was divided longitudinally, and total resection was achieved. Pathological diagnosis confirmed Pit-NET. The patient developed transient DI and transient worsening of visual field disturbance, both of which improved within 3 months postoperatively. LESSONS: Ectopic Pit-NETs can occasionally present with apoplexy, and preoperative differential diagnosis can be difficult based on imaging study alone. Intraoperative histopathological diagnosis could help prevent unnecessary endocrinological deficits. https://thejns.org/doi/10.3171/CASE24779.